COPD and lung cancer: underdiagnosis and clinical characterization

DOCTORAL THESIS COPD AND LUNG CANCER: UNDERDIAGNOSIS AND CLINICAL CHARACTERIZATION. Cecilia Mouronte Roibás ESCUELA DE DOCTORADO INTERNACIONAL PROGRAMA DE DOCTORADO EN EPIDEMIOLOGÍA Y SALUD PÚBLICA SANTIAGO DE COMPOSTELA 2019 DOCTORAL THESIS COPD AND LUNG CANCER: UNDERDIAGNOSIS AND CLINICAL CHARACTERIZATION. Signed_____________ Cecilia Mouronte Roibás ESCUELA DE DOCTORADO INTERNACIONAL PROGRAMA DE DOCTORADO EN EPIDEMIOLOGÍA Y SALUD PÚBLICA SANTIAGO DE COMPOSTELA 2019 DECLARACIÓN DEL AUTOR DE LA TESIS/ DECLARATION BY THE AUTHOR OF THE THESIS COPD and lung cancer: underdiagnosis and clinical characterization. Dña. Cecilia Mouronte Roibás. Presento mi tesis, siguiendo el procedimiento adecuado al Reglamento, y declaro que: 1. La tesis abarca los resultados de la elaboración de mi trabajo. 2. En su caso, en la tesis se hace referencia a las colaboraciones que tuvo este trabajo. 3. La tesis es la versión definitiva presentada para su defensa y coincide con la versión enviada en formato electrónico. 4. Confirmo que la tesis no incurre en ningún tipo de plagio de otros autores ni de trabajos presentados por mí para la obtención de otros títulos. I submit my thesis, following the procedure appropriate to the Regulation, and declare that: 1. The thesis covers the results of the preparation of my work. 2. When necessary, the thesis refers to any collaborations received for its preparation. 3. The thesis is the final version submitted for its defense and coincides with the version sent in electronic format. 4. I confirm that the thesis does not incur in any type of plagiarism of other authors or of works presented by me for any other title obtention. Santiago de Compostela, ………….……………….………………………..……….. Signed . ........................................................................... AUTORIZACIÓN DEL DIRECTORTUTOR DE LA TESIS/ AUTHORIZATION OF THE DIRECTOR-TUTOR OF THE THESIS COPD and lung cancer: underdiagnosis and clinical characterization. Alberto Ruano Raviña, PhD . Alberto Fernández Villar, MD, PhD. Virginia Leiro Fernández, MD, PhD. INFORMAN: Que la presente tesis, corresponde con el trabajo realizado por Dña. Cecilia Mouronte Roibás, bajo nuestra dirección, y a utorizamos su presentación , considerando que reúne los r equisitos exigidos en el R eglamento de Estudios de Doctorado de la USC, y que como directores de ésta no incurre en las causas de abstención establecidas en Ley 40/2015. Además, la presente tesis es idónea para ser presentada de acuerdo con el artículo 41 del Reglamento de Estudios de Doctorado de la USC, por la modalidad de compendio de ARTÍCULOS, en los que la doctoranda participó en el peso de la investigación, siendo su contribución decisiva para llevar a cabo este trabajo. Del mismo modo, esta tesis está en conocimiento de los coautores, tanto doctores como no doctores, participantes en los artículos, y ninguno de los trabajos reunidos en esta tesis serán presentados por ninguno de ellos en otra tesis doctoral, lo que firmamos bajo nuestra responsabilidad. INFORM: That this thesis corresponds to the work done by Mrs. Cecilia Mouronte Roibás, under our direction, and authorize its presentation, considering that it meets the requirements of the Reglamento de Estudios de Doctorado de la USC, and that, as directors of this work, it does not incur in the causes of abstention established in the Law 40/2015. In addition, the present thesis is suitable to be presented in accordance with article 41 of the Regulations of Doctoral Studies of the USC, by the modality of compendium of ARTICLES, in which the doctoral student participated in the the research, her contribution being decisive to carry out this work. Also, all co-authors are aware of the contents of this thesis, both doctors and non-doctors, participants in the articles, and none of the works gathered in this thesis will be presented by any of them in another doctoral thesis, which we sign under our responsibility Santiago de Compostela, ………….….………………………………………………….……….. Signed: Alberto Ruano Raviña Alberto Fernández Villar Virginia Leiro Fernández To my friends: Luís, Andrea and Dani, Naty and Sisqo, Adrián and Gary, Pablo and Marta and Maik, for all the shared moments, for their patience and for their trust and joy shared by each of the successes achieved, even from a distance. To Lourdes, wherever you are, for always reminding me "a que me atreva con las ocho". To my parents, for providing me with the best values and education. Also, for showing me that efforts are worthwhile, and for showing me how to become a hard-working, independent woman with my own criteria. I especially appreciate the effort to help me to become a physician, even in times when it did not seem easy. Thank you. To my grandparents, for believing their granddaughter is capable of "the impossible". Sara, for her interest on her cousin’s job, being still so young. To Marga and Luis, and to the rest of my in-laws, for welcoming me as one of them from the beginning. To David, my husband, for loving me, for sharing his life with me, for his priceless advice, for always being an example of patience and overcoming, for believing in me and, above all, for his unconditional support in all my projects, regardless of how complex and absorbing they may be. To the patients who participated in the studies. Thank you for trusting this team. This thesis has been carried out for them. PRESENTATION Lung cancer (LC) is the leading cause of cancer death in the world and is currently the most diagnosed neoplasm. In Spain, there were 28,645 new cases of cancer (more than 80% in men) in 2017. Chronic Obstructive Pulmonary Disease (COPD) is the fourth cause of death in the world, and it is estimated that it will be the third by 2020. COPD prevalence is around a 10%, although there is a high rate of underdiagnosis in general population. Many patients who smoke and, in particular, patients with COPD have pulmonary emphysema. Emphysema is a pathological lesion defined by the dilation of distal airways accompanied by their wall destruction. COPD prevalence in patients with LC has shown to be very variable among studies, ranging between 8 and 50%. Both diseases share smoking as a risk factor, in addition to other common pathogenic characteristics. It also seems that COPD may be a risk factor for LC development, independent of tobacco consumption. On the other hand, certain blood circulating molecules have been associated in COPD with higher mortality and exacerbations, and in cancer with a higher risk of malignancy, worse prognosis and worse response to treatment. In addition, there are data suggesting that the presence of emphysema increases the risk of developing LC, which reinforces the pathogenic relationship between COPD and LC. However, the role of emphysema in the relationship between the two diseases is not very clear. Despite of the existence of the mentioned associations, to date, information on whether patients with COPD and LC have any differential characteristics when compared to patients with COPD without LC that can explain an increase in carcinogenic susceptibility is lacking. There are no studies that analyze differences in their phenotypic characterization, multidimensional aspects or comorbidities, issues that are important for COPD phenotyping, as well as in the choice of targeted therapies and in the prognostic stratification of LC. It is also unknown how tumor stage impacts on COPD itself. On the other hand, although there are several types of emphysema, few studies have evaluated the relationship between each type and the risk of LC. According to the evidence on the potential association between COPD and LC (with or without emphysema), an investigation that allows to know epidemiological and clinical data has been carried out, in order to better characterize the interaction between both diseases. COPD prevalence and underdiagnosis in LC patients, and the profile of patients with COPD and LC were determined, comparing it with a control group of patients with COPD without LC, analyzing its phenotypic and multidimensional characterization. The finding of differential aspects could have a potential utility in LC screening in COPD patients, in LC early diagnosis, or even prognostic utility, being helpful in the treatment decision making process. This thesis is part of the project "COPD and lung cancer, underdiagnosis and clinical characterization" (110/2016) endorsed and funded by the Sociedad Española de Patología Respiratoria (SEPAR), and has been developed with the following aims: 1. To estimate COPD prevalence among patients with LC diagnosis, as well as the proportion of previously undiagnosed patients in whom COPD is detected in the spirometry performed at the time of LC evaluation. 2. To assess the differential clinical characteristics of patients with LC with or without concomitant COPD. 3. To evaluate the clinical profile of patients with COPD and LC, comparing it with a control group of patients with COPD without LC, in order to stablish their phenotypic and multidimensional characterization. 4. To search for blood inflammation markers with potential diagnostic, prognostic and therapeutic utility, with the objective of modifying future approaches to LC screening strategies. This work is structured in ten chapters. The introduction reviews the available evidence regarding the epidemiology of LC and COPD, as well as any risk factors that have been related to both diseases. In addition, a review of the available data on epidemiological and radiological characteristics of emphysema has been made. The second chapter presents the main and specific objectives proposed in this investigation. The third chapter refers to the characteristics of the subjects included in the studies, as well as the methods used for the development of this work. The following five chapters correspond to the results, showing four articles already published or pending publication in which, the results of this research are collected and analyzed. The first article is a systematic review of the articles published to date on the relationship between COPD, emphysema and LC. The second article shows the results of a multicenter study evaluating differential characteristics of COPD patients in a cohort of patients with LC diagnosis, whereas the third article presents with the results of a case-control study comparing cases with COPD and LC with a control group of COPD without LC. The fourth article is a case-control study comparing 16 biomarker levels in a group of cases with COPD and LC and two control groups: COPD without LC and LC without COPD. The aim of the cohort study is to estimate the prevalence and degree of underdiagnosis of COPD among patients with LC diagnosis, in addition to evaluating differential clinical characteristics of patients with LC and COPD and patients with LC without COPD. The aim of the case-control studies is to determine the clinical, radiological and biochemical profile of patients with COPD and LC, comparing it with another control group of patients with COPD without LC, to analyze its phenotypic and multidimensional characterization, to evaluate a possible relationship between a specific type of emphysema and the existence of LC in patients with COPD and to establish whether differential levels of blood biomarkers can predict which patients belong to the LC and COPD group. The penultimate chapter includes the discussion, which reflects the method and results obtained in this doctoral thesis and the last chapter reflects the conclusions of this work. Note: this is a thesis performed by the modality of compendium of articles, in which three studies already published in international journals are presented. The first article is a systematic review published in Cancer Letters, a first-quartile journal, with an impact factor of 6.491 occupying position 25/217 of Oncology journals in the Journal Citation Reports. The second article has been published in Respiration, a second-quartile journal, which has an impact factor of 2.591 and occupies position 31/59 of the Respiratory System journals and is the official journal of the European Association for Bronchology and Interventional Pulmonology. (EABIP). The third article has been published in the International Journal of COPD, a secondquartile journal, with an impact factor of 2.917 and ranking 25/59 among the Respiratory System journals. The fourth article has been sent to press, currently pending acceptance. Regarding the contribution of the doctoral candidate to the development of the published articles included in this thesis, in the case of the study "COPD, emphysema and the onset of lung cancer. A systematic review", she was responsible for carrying out the initial bibliographic search, as well as being one of the two reviewers of the aforementioned bibliography to verify that selected articles met the inclusion and exclusion criteria, she was also responsible for carrying out the data analysis, as well as the preparation of the manuscript and its submission for publication. In the article "Chronic Obstructive Pulmonary Disease in Lung Cancer Patients: Prevalence, Underdiagnosis and Clinical Characterization", the doctoral candidate took part in the data collection and analysis, in the study design, in the manuscript preparation and in its submission for publication. In the study "Influence of the type of emphysema in the relationship between COPD and lung cancer", the doctoral candidate took part in the conception and design of the study, performed the data acquisition as well as the analysis and interpretation of the data and developed the draft article with a critical review of its content, being also responsible for its submission for publication. In the article pending publication "Predictive value of a series of inflammatory markers in COPD for lung cancer diagnosis", the doctoral student took part in the choice of markers, in the selection of patients, in obtaining blood samples, in the analysis of the existence of emphysema, in the statistical analysis of the data, as well as in the design, elaboration, correction and sending of the manuscript. In all the articles included in this doctoral thesis, reference is made to the absence of any conflict of interest from the doctoral candidate or from any other coauthor of the mentioned works. The doctoral candidate has actively participated as first author in another publication, an editorial requested to our group after the publication of the first two articles included in this thesis, by the journal Translational Lung Cancer Research, entitled: "Lung cancer and chronic obstructive pulmonary disease: understanding the complexity of carcinogenesis ". The article is presented as an annex at the end of this thesis. Spanish summary (Resumen en español) En estos años se han publicado numerosos estudios que parecen mostrar la existencia de una relación entre el cáncer de pulmón (CP), la enfermedad pulmonar obstructiva crónica (EPOC) y el enfisema. Sin embargo, no existen estudios de caracterización fenotípica y multidimensional de los casos de EPOC con CP que nos puedan ayudar a elegir la terapia más adecuada y su pronóstico. Tampoco se ha estudiado la posibilidad de una relación entre distintos tipos de enfisema y la existencia de CP. Del mismo modo, existe escasa evidencia acerca del papel que representan algunos marcadores de inflamación en sangre, que podrían servir como herramientas de diagnóstico precoz, de posible cribado del CP, de determinación de gravedad, de evaluación de respuesta terapéutica y/o de toma de decisiones diagnósticas y terapéuticas en el subgrupo de pacientes con una EPOC de base. El objetivo de esta tesis es estimar la prevalencia de EPOC y su grado de infradiagnóstico en pacientes con CP, así como evaluar el perfil clínico de pacientes con EPOC y CP y compararlo con otro grupo control de pacientes con EPOC sin CP, para analizar su caracterización fenotípica, radiológica y multidimensional, teniendo en cuenta la poca literatura existente y sus resultados discrepantes. Los dos hallazgos más novedosos alcanzados en los trabajos que incluye esta tesis son que el enfisema paraseptal en pacientes con EPOC es más frecuente en el subgrupo de pacientes que además presentan CP, especialmente dentro del subgrupo de los adenocarcinomas, y que los niveles elevados de alfa-1 antitripsina y de neutrófilos y los disminuidos de colesterol, se asocian con una mayor probabilidad de presentar un CP en pacientes con EPOC. De hecho, el estudio de los biomarcadores nos ha permitido desarrollar una escala de riesgo que ha mostrado una elevada sensibilidad y valor predictivo negativo, con un área bajo la curva (AUC) cercana a 0,80. Teniendo en cuenta estos resultados sobre el enfisema paraseptal y los biomarcadores sanguíneos, este proyecto se intentará continuar con varios trabajos multicéntricos a nivel nacional. Estos estudios se diseñarán para validar prospectivamente nuestros resultados, con el objetivo de poder plantear una escala combinada de parámetros clínicos, exposiciones de riesgo, función pulmonar, tipo de enfisema y marcadores en sangre, que permita seleccionar a aquellos pacientes con EPOC susceptibles de ser la población diana en estrategias de cribado de CP. Como objetivo secundario, se pretende modificar las escalas predictoras de malignidad en el estudio de nódulos pulmonares y otras lesiones sospechosas de CP en pacientes con EPOC. INDEX CHAPTER 1. Introduction ....................................................................................................... 37 1.1. Lung Cancer epidemiology. ....................................................................................... 39 1.1.1. LC incidence. ................................................................................................... 39 1.1.2. LC mortality. .................................................................................................... 40 1.1.3. Sex and age. ..................................................................................................... 41 1.1.4. Histological type, molecular characterization and immunotherapy. ............... 40 1.1.5. Staging. ............................................................................................................ 41 1.2. Chronic Obstructive Pulmonary Disease (COPD) Epidemiology. ............................ 43 1.2.1. COPD incidence and prevalence ..................................................................... 43 1.2.2. COPD underdiagnosis. ..................................................................................... 47 1.2.3. COPD impact. .................................................................................................. 48 1.2.3.1. Mortality ................................................................................................ 48 1.2.3.2. Socioeconomic impact ........................................................................... 49 1.3 COPD and LC. ............................................................................................................ 50 1.3.1. Epidemiology ................................................................................................... 50 1.3.2. Common risk factors. ....................................................................................... 51 1.3.2.1. Tobacco ................................................................................................. 51 1.3.2.1.1. Active smoking ........................................................................... 52 1.3.2.1.2. Environmental exposure to tobacco smoke. ................................ 53 1.3.2.1.3. Electronic cigarette. ..................................................................... 54 1.3.2.2. Coal, biomass and environmental exposures. ........................................ 54 1.3.2.3. Laboral exposure and hobbies. .............................................................. 55 1.3.2.4. Diet. ....................................................................................................... 56 1.3.2.5. Alpha-1 antitripsin. ................................................................................ 57 1.3.3. Individual risk factors. ..................................................................................... 58 1.3.3.1. Risk factors for LC ................................................................................ 58 1.3.3.1.1. Radon .......................................................................................... 58 1.3.3.1.2. Family history and genetic exposure. .......................................... 58 1.3.3.2. Risk factors for COPD ........................................................................... 59 1.3.3.2.1. Gender and age ............................................................................ 59 1.3.3.2.2. Lung growth and development. ................................................... 59 1.3.3.2.3. Socioeconomic status. ................................................................. 60 1.3.3.2.4. Asthma and bronchial hyperreactivity. ....................................... 60 1.3.3.2.5. Infections. .................................................................................... 60 1.3.4. COPD as a risk factor for LC development. .................................................... 60 1.3.4.1. Inflammation. ........................................................................................ 61 1.3.4.2. Epigenetics and oxidative stress. ........................................................... 62 1.3.5. LC influence on COPD. ................................................................................... 62 1.4. Emphysema and LC. .................................................................................................. 63 1.4.1. Relationship between both entities. ................................................................. 63 1.4.1.1. Emphysema severity. ............................................................................. 64 1.4.1.2. Emphysema types. ................................................................................. 64 1.4.1.3. Emphysema location. ............................................................................ 65 1.5. Justification of the investigation ................................................................................ 65 CHAPTER 2. Justification and objectives. .............................................................................. 69 CHAPTER 3. Subjects and methods........................................................................................ 75 3.1. Design and Setting. .................................................................................................... 77 3.2. Inclusion Criteria. ...................................................................................................... 78 3.3. Exclusion Criteria. ..................................................................................................... 79 3.4. Sample Size Calculation. ........................................................................................... 79 3.5. Information Retrieval. ................................................................................................ 79 3.6. Statistical Analysis. .................................................................................................... 81 CHAPTER 4. Results ............................................................................................................... 83 CHAPTER 5. Results. COPD, emphysema and the onset of LC. A systematic review .......... 87 CHAPTER 6. Results. COPD in LC patients: prevalence, underdiagnosis and clinical characterization. ....................................................................................................................... 95 CHAPTER 7. Results. Influence of the type of emphysema in the relationship between COPD and LC. ................................................................................................................................... 107 CHAPTER 8. Results predictive value of a series of inflammatory markers in COPD for LC diagnosis................................................................................................................................. 119 CHAPTER 9. Discussion. ...................................................................................................... 143 9.1. Discussion: hypothesis and methods ....................................................................... 145 9.2. Discussion: results ................................................................................................... 146 9.3. Advantages of this thesis ......................................................................................... 151 9.4. Limitations of this thesis .......................................................................................... 152 9.5. Implications ............................................................................................................. 153 9.6. Future ....................................................................................................................... 154 CHAPTER 10. Conclusions. .................................................................................................. 157 REFERENCES....................................................................................................................... 163 ANNEX .................................................................................................................................. 185 ANNEX 1. Approval of the project by the galician ethics committee. .......................... 187 ANNEX 2. Example of registration of the emphysema by radiologists ......................... 191 ANNEX 3. Determination of inflammatory markers ("COPD profile"). ....................... 195 ANNEX 4. Editorial:LC and COPD: understanding the complexity of carcinogenesis. 199 ANNEX 5. Communications associated with this thesis. ............................................... 207 CHAPTER 1. INTRODUCTION Introduction 39 1.1. LUNG CANCER EPIDEMIOLOGY. Lung cancer (LC) represents about 13.5% of all tumors, being almost the most frequent worldwide, exceeded only by breast cancer, and it is the third cancer after colorectal and prostate cancer in Spain (1-4). Its survival at 5 years slightly exceeds 18%, being surgery the most favorable treatment in early stages, achieving a five-year survival of around 60% for stages I and II (3,5). 1.1.1. LC incidence. The most recent data on LC incidence worldwide are obtained through the World Health Organization (WHO) refer to the year 2012, whereas data from the International Agency for Research on Cancer (IARC, Globocan) refer to the year 2018, in which 2.1 million new cases of LC in the world were diagnosed (2,6). However, we have national and international statistics that allow us to estimate the impact of this disease. According to the Surveillance, Epidemiology and End Results Program (SEER), in 2018 there were 234,030 new cases only in the United States (USA) (3). Figure 1. LC incidence rates in the world in 2018 for both sexes. Source: International Agency for Research on Cancer (IARC). Globocan 2018. Permitted by The International Agency for Research on Cancer (IARC). In Spain, in 2017 there were 28,645 new cases of LC (81.5% in men and 18.5% in women, according to data from the Asociación Española Contra el Cáncer (AECC) and the Sociedad CECILIA MOURONTE ROIBÁS 40 Española de Oncología Médica (SEOM). In addition, although in recent years there has been a trend towards incidence stabilization in men, an increase in women is being observed (4,7,8). 1.1.2. LC mortality. As previously stated, LC limits survival, which currently stands around 15% for all LCs, and around 18.1% for non-small cell lung cancer (NSCLC), which is the group representing 80% of all LCs (3). Unfortunately, despite important advances in diagnostic and therapeutic techniques, survival rates have changed very little in recent decades (9-11). The high mortality derived from LC is the result of a high proportion of diagnoses in advanced stages, being possible to identify tumors in localized stages only in 16-22% of cases. On a positive note, several series report an increase in localized stages of LC at diagnosis, due to the existence of new diagnostic techniques, the easier access to them and the implementation of rapid diagnostic units (3, 12). In these cases, survival can reach up to 56.3% at 5 years (12). Figure 2. Mortality rates of LC worldwide in 2018 for both sexes. Source: International Agency for Research on Cancer (IARC). Globocan 2018. Permitted by The International Agency for Research on Cancer (IARC). Mortality rates vary widely between different countries, as LC is a disease in which mortality is directly proportional to the tobacco history of each country (10). In the USA, according to data from the SEER, in 2018 there were 154,050 deaths by LC (3). In our country, according to data from the Instituto Nacional de Estadística (INE), in 2016, 22,187 inhabitants died because of LC (17,424 men and 4,563 women) (13), with a global mortality of 19.4%, thus representing the cancer with the highest mortality in Spain (14). Introduction 41 1.1.3. Sex and age. LC is the most frecuent neoplasm causing mortality in men, being the third most common cause of death in women (13,15). The pattern of tobacco consumption in both men and women has changed in recent decades, leading to changes in the incidence rates of LC by sex, which have increased more in women than men in recent years. Nevertheless, LC is still a more frequent disease in men (15) and, in fact, in our country the male/female relationship is still high (4:1), although it is lower than it was two decades ago (10:1) (16,17). Cancers with higher mortality stratified by sex are LC and colorectal in males and breast and colorectal in women (14). Figure 3. Causes of cancer by sex in Spain in 2012: incidence and mortality. Figure of my own elaboration made from the data published in the source: International Agency for Research on Cancer (IARC). Globocan 2012. Due, in part, to the relationship of LC with smoking, and to the existence of a latency time between tobacco consumption and the development of disease, LC usually presents at 65-74 years, with a median age of 70 years at diagnosis (3). In Spain, the proportion of patients older than 70 years with newly diagnosed LC is greater than 50% (9). On the other hand, the incidence falls after 80 years, an age with a lower prevalence of smoking, in which there may be a survival bias derived from the existence of some type of genetic resistance to certain risk factors. The median age of patients dying from LC is 72 years (3,16). CECILIA MOURONTE ROIBÁS 48 Considering the results of the EPI-SCAN, according to the calculated prevalence, 2,185,764 Spaniards aged between 40 and 80 years would have COPD (1,571,868 men and 628,102 women). However, taking into account that 73% are still not diagnosed, more than 1,595,000 Spaniards still do not know that they have the disease and also do not receive any specific treatment for it (41). Currently, the new EPI-SCAN II study is developing, and it will provide more up-to-date information on the prevalence and underdiagnosis of this disease in Spain. 1.2.3. COPD impact. 1.2.3.1. Mortality COPD is the fourth cause of death in the world and, just as the prevalence is expected to increase in the next 30 years, the same will occur with mortality, which is why the WHO estimates that in 2030 it will be the third cause of death worldwide, with more than 4.5 million deaths per year due to COPD and its complications (43). However, we know that COPD is one of the most important causes of death already, being the third one in the USA. (44) Figure 6. COPD deaths per 100,000 inhabitants, for both sexes and all ages, year 2016. (Source: Adapted from the Global Burden of Disease). Creative Commons Licence. Introduction 49 In 2008, chronic diseases of the lower respiratory tract represented the fourth cause of death in Spain (11.4% of total deaths), surpassed only by cancer (26.1%), heart disease (20.8%) and cerebrovascular diseases (18.2%) (45). According to data from the Global Burden of Disease in 2016, COPD accounted for 5.36% of all deaths worldwide, (5.66% [5.36-5.91%] of all deaths in men and 5.01% [4.61-5.67%] of all deaths in women) (46). 1.2.3.2. Socioeconomic impact Given that COPD is a chronic and progressive disease, it implies a significant loss of quality of life for our patients. The DALYs (Disability-Adjusted Life Years), are the sum of years lost due to premature mortality and the years lived with disability, adjusted for the severity of it. The Global Burden of Disease study found that COPD is currently the fifth cause of DALYs lost worldwide and it is the second cause of loss of DALYs in the USA, surpassed only by coronary heart disease (47-49). On the other hand, the chronicity of COPD also determines a high cost derived from the consumption of health resources, with multiple visits to consultations, emergencies and hospitalizations. In Spain, according to the Registro de Altas de los Hospitales Generales del Sistema Nacional de Salud (SNS) of 2010, there were 58,066 hospital discharges in relation to COPD, with an average stay of 8.25 days (45). The estimated costs reviewed in the document Estrategia EPOC of the SNS in Spain were of 750-1,000 million euros per year, including direct, indirect and intangible costs. The direct costs were distributed in hospital expenses (4045%), pharmacological expenses (35-40%) and visits and diagnostic tests (15-25%) (45). In the European Union, the total direct costs for respiratory disease account for 6% of the total budgeted for healthcare, with COPD accounting for 56% of the whole (38.6 billion euros) (50). In the USA. the estimated direct costs are 32 trillion dollars and the indirect costs are 20.4 trillion dollars, with COPD exacerbations receiving a greater percentage of the budget (51). CECILIA MOURONTE ROIBÁS 50 1.3 COPD AND LC. 1.3.1. Epidemiology As previously discussed, both LC and COPD share a series of common characteristics, such as a high mortality, with important associated comorbidity. In addition, both diseases have a series of common risk factors such as smoking, genetic alterations, environmental exposures and inflammation (52,53). COPD is a common comorbidity among patients with LC (54,55), with a very variable prevalence among studies, ranging between 28 and 40%, due mainly to methodological differences in COPD definition, some of them not clearly stating the difference between COPD and emphysema, and also because of the high underdiagnosis of this disease, both in patients with LC and in general population (56,57). In addition, evidence of an association between COPD and the development of LC has been observed in population studies, LC screening studies, and case-control studies (58-61). The first studies demonstrating a relationship between COPD and LC were performed in the 1980s, when Skillrud et al. (62) and Tockman et al. (63) described an increase in the incidence and mortality of LC in patients with airflow obstruction. Several subsequent studies have confirmed this fact, with an increase of between 2 and 4 times in the risk of developing LC (60,64-67). In a recent meta-analysis (68), a strong association was found between FEV1 decline and LC. Compared with the highest quintile of FEV1 (>100% of predicted), the lowest quintile (<70% of predicted) was associated with an increased risk of LC. In patients with COPD, even a small decrease in predicted FEV1 (below 90%) showed a higher risk of developing LC [OR 2.56 (95% CI 1.29-5.07)]. COPD underdiagnosis is very high in most series, both in the general population and in patients with LC, where some studies have shown a previous diagnosis of COPD of 7.1% (69). Despite the availability of national and international guidelines, COPD remains underdiagnosed in patients with LC, which implies serious delays in diagnosis and treatment and, therefore, in the prognosis of these patients. COPD in patients with LC may pose certain limitations when it comes to LC treatment. One of the consequences is that patients are inoperable, due to a functional limitation. In addition, COPD increases the frequency of all postoperative complications, such as pneumonia Introduction 51 (10.1-16.2% after surgery) (70-72), atelectasis (3.5-15.4%) (72,73) , empyema (2.2-8.3%) (71) and persistent air leak (12-16.2%) (70,74). One option in patients with surgery limitations is the SBRT (Stereotactic body radiation), which justifies once again the importance of knowing if the patient has COPD in order to decide the best option for LC treatment. There are few studies that have investigated the effect of COPD in patients with advanced forms of LC. The presence of COPD has not shown a prognosis worsening in patients with chemo or immunotherapy, nor changes in the quality of life (75). Most studies show that COPD implies an unfavorable effect on LC prognosis (71,76,77), although some show differently (75,78). Two recent meta-analyzes indicate that COPD is an unfavorable prognostic factor, although there was a significant heterogeneity between studies included in them (79). A prognostic model (COPD-LUCSS-DLCO) has been designed to identify patients with COPD and an increased risk of dying from LC (80). Patients were divided into two risk groups based on a score obtained from the combination of their age, body mass index (BMI), smoking and DLCO (diffusing capacity of carbon monoxide). Patients in the high-risk group were 2.4 times more likely to die than the low-risk group. 1.3.2. Common risk factors. 1.3.2.1. Tobacco Figure 7. Figure of my own elaboration made from the data published in the source: Ministerio de Sanidad, Servicios Sociales e Igualdad. Source: EESE 2014-2017 (INE), ENSE 2003-2011 (MSSSI/INE), EES 2009 (INE/MSSSI) and ENS 1993-2001 (MSSSI). 44 43.5 42.1 39.2 34.2 31.6 31.2 27.9 27.6 25.6 20.8 24.5 24.8 24.7 22.4 21.5 21,3 20.2 18.6 18.8 38.6 33.8 36 36,9 34.2 25 28.9 22.5 21.6 20 33.8 40.5 34.5 36.9 31.1 25 21.3 21 15.5 15.1 0 5 10 15 20 25 30 35 40 45 50 1993 1995 1997 2001 2003 2006 2009 2011 2014 2017 Daily smokers Adult population (16+years until 2009; 15+years until 2011). ENSE/EESE 19932017 Men over 15 years Women over 15 years Men 15-24 years Women 15-24 years CECILIA MOURONTE ROIBÁS 52 The smoke emitted by tobacco gathers more than 4,000 different substances, with more than 60 carcinogens, such as polycyclic aromatic hydrocarbons, aromatic amines, nitrosamines (which are substances with potential capacity to irreversibly alter DNA), chloride vinyl, benzene, chromium or arsenic (81). Some of the aforementioned substances produce mutations that may persist after smoking cessation, which could partially justify the elevated risk of LC in former smokers (81). 1.3.2.1.1. Active smoking In the last decades, multiple strategies have been developed to reduce tobacco consumption (82). However, smoking prevalence worldwide remains high. In the USA, it currently stands at 13%, and in Europe there is a greater consumption in Eastern and Southern countries, Spain being among the countries with the highest prevalence, close to 30% (81). According to the National Health Survey of 2017, 25.58% of men and 18.76% of women are active smokers, 24.93% of the Spanish population being former smokers (32.23% of men and 18.02% of women) (83). In recent years the prevalence of smoking in men has dropped, while in women the prevalence of smoking has remained stable, and the number of young people who start smoking is still high. In Spain, in 2016, the number of young people smoking increased by 50,000 when compared to 2014, most of them being over 14 years of age. There were no significant differences by sex at the beginning of the consumption. For the first time, the average age of onset of tobacco use has been delayed until 14.1 years, which implies a progressive delay of one year in the first contact with this substance, which in 2006 stood at 13.1 years, according to data from the ESTUDES 2016-2017 survey (84). As previously mentioned, since tobacco is a risk factor for LC development, a latency time between consumption and the development of the disease is necessary. This time is estimated, on average, in 30 years. A Spanish study observed that the increase in the prevalence of smoking 32 years earlier was associated with the peak of mortality due to LC between 2006 and 2013, due to the fact that, according to surveys of the SNS, the prevalence of smoking increased a 7% between 1974 and 1981, and only 3.8% from 1981 to 1988. On the other hand, smoking in women reached its peak in the mid-90s, so that LC mortality in women is expected to continue increasing until the year 2026 (85). Introduction 53 The risk of developing diseases related to tobacco consumption, such as COPD or LC, depends on the latency time, but it will also be proportional to the number of cigarettes smoked, to the age of onset of smoking (with a higher risk at a younger age), to the degree of inhalation, to the amount of carcinogenic particles inhaled, or to the existence of unfiltered cigarettes, with an important cumulative effect (86). Up to 13% of patients with LC continue to smoke despite the severity of the diagnosis. This group presents several risk characteristics such as younger age, depression and living with a smoker (87). Tobacco is a risk factor for the development of any type of LC, although its association with squamous and small cell types is still more marked (88). Several studies have estimated that the absolute risk of developing COPD among smokers is between 25 and 30% (89). In addition, the risk is proportional to the accumulated consumption of tobacco, going from 26% in smokers of 15-30 packs a year to 51% in smokers of more than 30 packs a year (87). 1.3.2.1.2. Environmental exposure to tobacco smoke. The information available about this exposure is variable among studies, not only because of the different patterns of tobacco consumption between countries, but also because of the difficulty in quantifying and recording it. However, in Europe, exposure to second or third-hand tobacco ranges from 8% in Sweden to 68% in Russia and Greece. Spain is in the group of countries with the highest exposure (around 50%), although strategies such as the Ley Antitabaco (82) help to minimize this fact. Exposure to second or third-hand tobacco smoke causes LC in never smokers. Not only is it biologically plausible, but also, the urinary excretion of carcinogens such as nitrosamine has been demonstrated in patients exposed to environmental tobacco smoke (81,90). Several epidemiological studies show an excess risk of LC of 24% in never smokers exposed to environmental tobacco smoke, with the effects observed being dose-dependent (81,91). Among never smokers, passive smoking is a risk factor involved in the pathogenesis of COPD (92,93). A study with more than 6,000 participants (mostly women), in which more than half claimed to be passive smokers, showed that the duration of passive smoking was directly related to the risk of developing COPD (93). CECILIA MOURONTE ROIBÁS 54 1.3.2.1.3. Electronic cigarette. Electronic cigarettes were developed more than a decade ago and were designed to provide nicotine without the need to burn tobacco. In Europe, 7% of smokers in the countries included in the Eurobarometer (system of public surveys carried out by the European Commission) had once used the electronic cigarette, 1% of them using it regularly (94,95). Figure 8. Electronic cigarette functioning. Figure of my own elaboration drawn from the information given by SAMHSA, VERISPAN. With the use of electronic cigarettes, exposure to various substances occurs. The liquids contain nicotine in a glycerol or propylene glycol flavored medium. Glycerin has been linked to a case of lipoid pneumonia (94). In addition, the vapor of the electronic cigarettes contains carcinogenic substances such as formaldehyde, acetaldehyde or acroleins. It is known that electronic cigarettes provide nicotine levels similar to or even higher than those emitted by the conventional cigarette (96,97). It also contains fine particles in suspension, <2.5 microns (PM2.5) that are harmful for both active and passive smokers (94,95). 1.3.2.2. Coal, biomass and environmental exposures. Despite the important technological and industrial revolution that the planet has witnessed in the last century, striking socio-economic differences persist that imply that up to 40% of the Introduction 55 world's population is dependent on the use of biomass as fuel to meet their energy needs for cooking and heating their homes, especially in developing countries. There are several fuels of biological origin such as wood, coal, crop residues and manure (91). In several reviews, biomass and other fuels have been identified as risk factors for COPD, especially in rural areas (33,98,99). A systematic review showed that the risk of developing COPD in people exposed to biomass is 2.44 times higher than that of people who are not exposed, regardless of sex and smoking burden (100). The IARC in 2006 classified the emissions derived from the use of fuels from biomass as 2A carcinogens (91). A case-control study conducted in Europe and the USA (101) found an increased risk of LC in people exposed to wood combustion smoke, with an OR of 1.21 (95% CI: 1.06-1.38). In addition, there could be a possible synergistic effect between tobacco and biomass (102). A meta-analysis (103) found an OR for the development of LC by exposure to biomass smoke of 1.21 (95% CI: 1.05-1.39, p=0.01) for men and 1.95 (95%CI: 1.16-1.37; p=0.01) for women. Similarly, recent decades have been accompanied by a striking increase in environmental pollution, which includes multiple carcinogenic substances, with a potential association with the increased risk of LC in studies published in the last 50 years, although the results are heterogeneous due to large geographical differences in pollution levels (104,105). In fact, the European Study of Cohorts for Air Pollution Effects (ESCAPE) (106) showed a significant association between the risk of LC and PM10 exposure, finding an association with the histological subtype adenocarcinoma (HR 1.51; 95% CI: 1.10-2.08 for PM10 and HR1.55, 95%CI: 1.05-2.29 for PM2.5). Pollutants that have been especially linked to COPD are ozone, PM, carbon monoxide, sulfur dioxide, nitrogen dioxide and other gases. High air pollution, especially in relation to vehicles, is a trigger for COPD exacerbations in susceptible individuals. Some studies have speculated on the possible influence of internal radon exposure on COPD admissions and on the prevalence of the disease, although these data should be confirmed in more robust investigations currently underway (107). 1.3.2.3. Laboral exposure and hobbies. LC has been related to several work-related diseases, such as silicosis or exposure to CECILIA MOURONTE ROIBÁS 56 asbestos, although it is also associated with other elements such as radon, polycyclic aromatic hydrocarbons and certain metals (cadmium, chromium and arsenic). In fact, more than 20% of workers in the European Union are exposed to carcinogens in their jobs, especially in works such as carpentry, painting, metallurgy or construction (108). In recent years, measures have been established jointly with workers and companies, aimed at limiting occupational exposure to different substances (108). However, it is estimated that, worldwide, in the year 2000, 10% of deaths from LC in men and 5% in women were attributable to 8 lung carcinogens of occupational origin: arsenic, asbestos, beryllium, cadmium, chromium, diesel fumes, nickel and silica (109). Likewise, certain hobbies may involve exposure to certain carcinogens, often occurring for years, without the amateurs who practice them being aware of the potential risk to their lungs (110). It is known that hobbies or occupational exposures to certain fumes can be related to a worsening of COPD, although they have not been clearly established as risk factors to develop the disease in the first place (28,29). 1.3.2.4. Diet. There are multiple studies evaluating the influence of diet (meats, fish, fruits, vegetables and alcohol) on the risk of developing LC, with very different results. A case-control study (111) found that red meat consumption was associated with a protective effect (OR 0.24, 95%CI: 0.11-0.50), while fish consumption showed an association with the development of LC, with an OR of 1.67 (95%CI: 0.99-2.81), for both white fish and blue fish. Regarding the consumption of fruits and vegetables and the risk of LC, only a non-significant trend towards the reduction in the risk of LC was observed for green leafy vegetables and other vegetables such as potatoes (112,113). The effect that alcohol consumption could have on the risk of developing LC is controversial. A study published in 2004 (114) observed that the consumption of red wine showed a protective effect (OR 0.43, 95%CI: 0.19-0.96), whereas there was a discrete increase in the risk associated with the consumption white wine (OR 1.20 daily for each glass consumed). Another more recent study found that the consumption of any type of wine had a relationship with LC development, with an OR of 2.2 (95%CI 1.13-3.23). In the case of beer, Introduction 57 the OR was 1.33 (95%CI 0.82-2.14). These results were similar when the risk for women was analyzed separately. However, in the case of men, no increase in risk was observed for any of the analyzed beverages. No dose-response pattern was found (115). Recent evidence indicates that diet can play an important role in the development of COPD. It seems that a healthy diet based on the consumption of fruits, vegetables, cereals and fish has been associated with a lower risk of deterioration of lung function and COPD development (116,117). A cohort study conducted in Switzerland with 44,335 patients aged 45-79 years with no history of COPD at baseline found that an increase in a daily ration of fruit and vegetable consumption significantly reduced the risk of COPD by 8% among current smokers and 4% among ex-smokers (118). 1.3.2.5. Alpha-1 antitripsin. The main activity of alpha 1 antitrypsin (A1AT), a glycoprotein encoded by the serpin 1 gene, is the inhibition of neutrophil elastase and other proteases, although several properties of this protein have been described in recent years, such as its anti-inflammatory and immunomodulatory capacity (119). The congenital deficiency of alpha-1-antitrypsin (AATD) predisposes to an accelerated decrease in lung function (120,121). It is estimated that it is responsible for 1% of COPD cases and 2-4% of emphysema cases (120). In fact, every patient with COPD should have at least one determination of A1AT in their life (122). Possible carcinogenic mechanisms have been proposed for which the AATD could increase the risk of LC, the majority derived from an excess in the neutrophil elastase’s activity (119), which induces lung tissue damage due to a protease-antiprotease imbalance. It could also be due to the inhibition of apoptosis or the activation of matrix metalloproteases. The results of the few studies that have analyzed the possible relationship between the AATD and the risk of LC are discordant and they have biases in their design, since they include both smokers and former smokers (123-125). In a Spanish study performed in never smokers (126) a significant increase in the risk of LC in carriers of the S allele in homozygosis was demonstrated. For all these reasons, more studies are now needed to establish if there is an association between the AATD and the risk of LC. CECILIA MOURONTE ROIBÁS 64 1.4.1.1. Emphysema severity. There is no validated criteria to quantify the severity of emphysema and, therefore, we do not have data that allow us to establish a clear association between the severity of emphysema and the development of LC. Using automatic quantification, the studies by Kishi et al. (64) and Maldonado et al. (67) did not find any association. However, Wilson et al. (60) and Li et al. (179) found that mild emphysema predicted LC risk better than moderate-severe emphysema. In another study in a US screening cohort, they found a linear association between the severity of emphysema and the risk of death from LC. However, this association was only significant for extensive emphysema (more than half the lung parenchyma) (180). Some studies use the same scale to rate the severity or extent of emphysema, as reflected in the National Emphysema Treatment Trial (NETT) guidelines (0: no emphysema, 1: 0-25%, 2: 25-50%; 3 : 50-75%; 4: 75-100%) (176,181). 1.4.1.2. Emphysema types. Figure 9. The four images in this figure correspond to four axial slices of a pulmonary CT. The first (a) corresponds to an image of centrilobular emphysema, the second (b) shows an area of paraseptal emphysema, the third (c) shows an image of panacinar emphysema, and the fourth (d) shows the existence of a pulmonary bulla. Figures (a) and (c) have been adapted from Hansel et al. Fleischner Society: Glossary of Terms for Thoracic Imaging. Radiology. 2008; 246 (3):697-722, permitted by Radiology, whereas Figures (b) and (d) belong to two patients in our database which gave specific written informed consent for the anonymized publication of their images.. Introduction 65 There are several types of emphysema, although there is no clear evidence about its relationship with the development of LC or other types of disease (162). Centrilobular emphysema was defined as a dilation of the airway centered in the respiratory bronchiole; paraseptal emphysema as changes in the more distal alveoli adjacent to the pleural surface or to the interlobular septa; panlobular as that distributed throughout the pulmonary lobe; cicatricial as that settled on areas in which there has been some previous type of inflammatory process that has conditioned residual changes in the lung tissue; and bullae are defined as localized areas of emphysema greater than one centimeter in diameter (162,176,182184). The centrilobular emphysema is usually associated with a more advanced age, heavier smoking and severity (162,185), while the paraseptal predominantly affects the upper lobes (2,186) and is associated with male sex, older age and interstitial pathology, occurring more frequently in cases with the emphysema-fibrosis combination (162,185). Typically, paraseptal emphysema is not clinically relevant until it is in advanced stages (186) and has not shown any relationship with the development of symptoms in COPD, with the degree of obstruction or with smoking history (162,185). Panacinar emphysema is common in young patients, is associated with lower BMI and more severe COPD (162,187,188). 1.4.1.3. Emphysema location. Dividing the lungs into different segments and assigning specific scores for emphysema, a correlation was observed between the severity of regional emphysema and the chances of developing cancer in that specific location (189). Similarly, Hohberger et al. (176) found that, when comparing the location of a malignant nodule with other lung regions of the same patient, the likelihood of having a more severe emphysema in the area where LC was present was significantly higher: OR 1.34 (95%CI: 1.11-1.62). When comparing the location of a benign nodule with other areas of the lung in the same person, the chances of having a more severe emphysema in the areas where the benign nodule was located were 1.11 (95%CI: 0.72-1.72). 1.5. JUSTIFICATION OF THE INVESTIGATION As it has previously been stated, COPD and LC are high-impact health diseases that share common risk factors, specially smoking. Despite the great advances that have taken place in CECILIA MOURONTE ROIBÁS 66 the knowledge of both diseases, there are a number of aspects that have been very little analyzed so far, which could have an impact on the healthcare environment. The existence of an association between LC and COPD is an issue under discussion and the available data on the level of underdiagnosis of COPD in patients with LC and its phenotypic and multidimensional characterization is scarce or nonexistent. For this reason, we consider the study of the interrelation of both diseases pertinent and relevant, in order to generate the necessary scientific bases to better understand the interrelation between both pathologies, being able to transfer the results of the research to the clinical practice. CHAPTER 2. JUSTIFICATION AND OBJECTIVES. Justification and objectives 71 COPD and LC are two diseases with high morbidity and mortality (3,29,42). The high prevalence of patients suffering from both diseases suggests that there may be common etiological mechanisms, not only pathogenic but also genetic (190). Their interrelation is controversial and there are authors who have published studies in an attempt to verify whether COPD is a true risk factor for LC development or if both diseases are the result of common etiological factors, such as inflammation (53). As already explained in the introduction, several studies have shown that COPD is one of the main risk factors for LC development, regardless of sex, age, occupation or tobacco exposure, multiplying the risk from 4 to 6 times, when compared with smokers who maintain an adequate respiratory function (15,178). These probabilities seem to increase as FEV1 decreases, independently of smoking (68). On the other hand, COPD is one of the complications of LC that implies greater morbidity and mortality (191,192). Regarding the presence of emphysema, although several studies consider it a risk factor for LC development, it remains a controversial issue since other works do not report the same finding (193). So far, it has not been studied whether patients with COPD and LC have any differential characteristics compared to patients with COPD without LC, in terms of their phenotypic characterization, multidimensional aspects or comorbidities, issues that are key in the new vision of LC, with implications in the choice of targeted therapies and in the prognostic stratification. It is also unknown how the stage of the neoplastic disease impacts on COPD, a fundamental aspect in the clinical evolution of this disease. On the other hand, although there are several types of emphysema, there is no clear evidence about its relationship with LC development. Certain inflammatory markers have been associated in COPD with increased mortality and exacerbations, as well as with the risk of progression and worse prognosis in LC (194-203). The finding of common biomarkers that can establish prognostic and therapeutic response categories would be an important tool in decision making and could even mean the identification of COPD patients at risk of developing LC. For this reason and based on the potential association between COPD and LC, this thesis was designed to carry out research in order to better understand the interaction between both CECILIA MOURONTE ROIBÁS 72 diseases, as well as establishing whether there is any relationship between the type of pulmonary emphysema and the development of LC or some biomarker that may suggest a greater risk of belonging to the group of patients with COPD and LC. Having clinical, functional, imaging or biochemical predictors to detect patients with COPD who also have LC, would help to avoid unnecessary invasive procedures (or even to detect early LC) in these cases. The general objective of the project is to estimate COPD prevalence and its degree of underdiagnosis in patients with LC, as well as to evaluate the clinical profile of patients with COPD and LC, comparing it with another control group of patients with COPD but without LC, analyzing its phenotypic and multidimensional characterization and looking for a potential utility in the early detection of LC in patients with COPD or even with therapeutic or prognostic implications. The following specific objectives were established: 1. To estimate COPD prevalence among patients with LC diagnosis, as well as the degree of COPD underdiagnosis in this group (previously undiagnosed patients in whom COPD was detected in the spirometry performed at the time of LC diagnosis). 2. To analyze, within patients with LC, the differential clinical characteristics of patients with concomitant COPD. 3. To evaluate the clinical profile of patients with COPD and LC, comparing it with another control group of patients with COPD without LC, analyzing their phenotypic and multidimensional characterization. 4. To assess if there is a relationship between a specific type of emphysema and the existence of LC in patients with COPD. 5. To compare a series of inflammatory markers between patients with COPD and LC and patients with COPD without LC to be able to propose a hypothesis to establish a possible early detection strategy for LC in COPD patients. CECILIA MOURONTE ROIBÁS 80 4. LC characteristics: histological type (SCLC and NSCLC, adenocarcinoma, squamous cell carcinoma or large cell carcinoma) and TNM stage according to the current edition at the time of the study (27,204). 5. COPD characteristics: severity according to the GesEPOC guidelines (Spanish COPD guidelines) and GOLD (Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease) valid at the time of the study (29,42), in addition to recording the number of moderate exacerbations and hospitalizations for COPD in the last year and an assessment of the impact of the disease on quality of life through the COPD Assessment Test (CAT). 6. Emphysema characteristics: the presence of emphysema in thoracic CT was evaluated within the group of patients with COPD (with or without LC). The CT studies were carried out in two equipments: Lightspeed VCT of 64 rows of detectors (GE Medical Systems, Milwakee, Wisconsin) and Somatom Emotion of 16 rows of detectors (Siemens Medical Solutions, Enlargen, Germany). A qualitative and quantitative analysis of the type of emphysema was carried out, as well as the existence of different types of it, its affectation by lobes and its severity. 7. Relationship between COPD and LC: the COPD-LUCSS-DLCO scale described by DeTorres (80) was calculated. 8. Analytical: Peripheral venous blood samples of all patients were extracted. The serum concentrations of IL-6, IL-8 and TNF-α were determined by validated immunoassays (IMMULITE ONE, Siemens, Germany), complete blood counts were performed using ADVIA 2120 (Siemens, Germany), serum CRP, cholesterol and bilirubin were measured using ADVIA 2400 (Siemens, Germany); A1AT was analyzed by nephelometric assay (IMMAGE, Beckman Coulter, U.S.A.). IgE levels were measured by fluorometric immunoassay (PHADIA 250, Thermo Scientific, USA) and fibrinogen was calculated in the ACL TOP 700 instrument (Werfen Company, Spain). The detection limits (DL) for IL-6, IL-8 and TNF-α were 2 pg/ml, 5 pg/ml and 4 pg/ml. To avoid a downward bias of the data obtained, a nominal level of half the DL value in the analysis was used in individuals with values lower than the LD (205). Subjects and methods 81 3.6. STATISTICAL ANALYSIS. A descriptive analysis of all the included variables was carried out. Subsequently, bivariate analyzes were performed to evaluate the differences between groups. Student's t was used for quantitative variables and the χ2 test for qualitative variables. The significance limit was p <0.05. The significant variables in the bivariate analysis were included in a logistic regression model, expressing the data as OR with 95% confidence intervals. The Kaplan-Meier method was used to perform survival estimates. In the third study, two multivariate logistic regression models were performed, the first adjusting by age and sex and the second including the significant variables in the first. To do this, the quantitative variables were stratified into tertiles for inclusion in the logistic regression models. This led to the design of a risk variable for each patient based on the results of the logistic regression. Subsequently, a ROC curve was developed to evaluate the sensitivity, specificity and predictive values of the risk variable, taking into account a prevalence of LC in patients with COPD of 25% (15). The analysis was performed with the SPSS 21.0 program (IBM Corporation, Armonk, New York). CHAPTER 4. RESULTS Results 85 This section presents the results in 4 chapters, each of them reflecting the different studies resulting from this thesis: 1. CHAPTER 5. “COPD, emphysema and the onset of lung cancer. A systematic review”. The results of this study show that COPD and emphysema appear to increase the risk of developing LC, this risk being higher for patients with greater tobacco consumption. 2. CHAPTER 6. “COPD in lung cancer patients: prevalence, underdiagnosis and clinical characterization”. The results of this study show that COPD is a prevalent and highly underdiagnosed disease among LC patients. Cases with COPD and LC have a higher prevalence of squamous cell carcinoma, more comorbidities and lower KCO. 3. CHAPTER 7. “Influence of the type of emphysema in the relationship between COPD and lung cancer”. The results of this study show that paraseptal emphysema is more frequent in patients with COPD and LC, especially in those cases with the adenocarcinoma subtype 4. CHAPTER 8. “Predictive value of a series of inflammatory markers in COPD for lung cancer diagnosis”. The results of this study show that patients with COPD and LC have higher levels of neutrophils and A1AT and lower concentrations of cholesterol, having developed with their combination a scale that predicts the risk of belonging to the group of patients with COPD and LC. CHAPTER 5. RESULTS. COPD, EMPHYSEMA AND THE ONSET OF LC. A SYSTEMATIC REVIEW CHAPTER 6. RESULTS. COPD IN LC PATIENTS: PREVALENCE, UNDERDIAGNOSIS AND CLINICAL CHARACTERIZATION. CHAPTER 7. RESULTS. INFLUENCE OF THE TYPE OF EMPHYSEMA IN THE RELATIONSHIP BETWEEN COPD AND LC. CECILIA MOURONTE ROIBÁS 126 in the study. Variables were included in an anonymized database to maintain the principles of confidentiality and data protection. Information retrieval Collected data included basic demographics: age, gender, tobacco history, functional variables (comorbidity assessed by the Charlson Comorbidity Index17, FEV1, DLCO and body mass index (BMI). The histological type of LC was also included by reviewing the pathology report, as well as the stage at diagnosis according to the TNM eight edition's descriptors15 after complete staging processes. Other data necessary for COPD characterization were included, such as the GOLD and Spanish Guideline for COPD (GesEPOC) classifications valid at the study onset16,18, COPD assessment test (CAT)19 and BODEx index20. Smokers were defined as participants who had smoked 100 or more cigarettes in their lifetime. Current smokers were those who smoked more than one cigarette in the month prior to enrollment or quit within one year of enrollment. The remaining smokers were classified as ex-smokers. Never smokers were defined as having smoked less than 100 cigarettes in their lifetime21. Spirometry was performed at the time of inclusion in the study by a technician specialized in respiratory functional tests. It was carried out with a Masterlab pneumatic-type spirometer (Jaeger AG, Wuezburg, Germany), using acceptability and reproducibility criteria from SEPAR and ERS22 guidelines, with Quanjer Gli reference values23. A bronchodilator test was performed in all cases, by administrating 400 µg of salbutamol in 4 puffs (100 µg per puff) at 30 s intervals. Emphysema was determined through computed tomography (CT) assessment by experimented radiologists. The CT studies were performed in two devices: Lightspeed VCT of 64 rows of detectors (GE Medical Systems, Milwaukee, Wisconsin) and Somatom Emotion of 16 rows of detectors (Siemens Medical Solutions, Enlargen, Germany). Peripheral venous blood was collected from all patients into Vacutainer tubes in the morning. Serum was obtained by centrifugation of whole blood at 3,000 g for 10 minutes. Plasma (CITRATE as anticoagulant) was obtained by centrifugation at 3,500 g for 15 minutes at a temperature of 4ºC. Serum samples used to measure IL-6, IL-8 and TNF-α levels were stored at -80ºC until they were analyzed. IL-6, IL-8 and TNF-α serum concentrations were Predictive value of a series of inflammatory markers in COPD for LC diagnosis 127 determined by validated immunoassays (IMMULITE ONE, Siemens, Germany), full blood counts were carried out using ADVIA 2120 (Siemens, Germany); serum CRP, cholesterol and bilirubin were measured using ADVIA 2400 (Siemens, Germany); A1AT was analyzed by nephelometric assay (IMMAGE, Beckman Coulter, USA); IgE levels were measured by fluorometric immunoassay (PHADIA 250, Thermo Scientific, USA) and fibrinogen was calculated in ACL TOP 700 instrument (Werfen Company, Spain) Limits of detection (LOD) for IL-6, IL-8 and TNF-α were 2 pg/ml, 5 pg/ml and 4 pg/ml. Biomarker concentrations were below the LOD in some individuals. To avoid a downward bias of the population data, a nominal level of half of the LOD value was used in the analysis in individuals with values below the LOD24. Statistical analysis We first carried out a descriptive analysis of levels of all markers in the three groups of patients through the use of boxplots. Then we developed a univariate analysis to evaluate differences between cases (patients with LC+COPD) and controls (COPD) for all assessed variables. The t-student test was used for quantitative variables and Chi2 test was used to compare percentages for qualitative variables. Our limit of significance was p<0.05. We included variables with a p<0.10 in the multivariate models (performed through a forward conditional method), developing interaction analyses for all of them. For the final significant variables, we performed two multivariate logistic regression models, the first adjusting for age and sex and the second also including the remaining variables. To do so, the significant quantitative variables were stratified into terciles for inclusion in the logistic regression models. Application of this multivariate analyses led to the design of a risk score variable for each given patient based on the results of the multivariate logistic regression. Points for a given patient were obtained by summing all the points for each predictor variable, adjusted for sex and age. Then we developed a ROC curve and assessed sensitivity, specificity and predictive values for the risk score variable, considering a prevalence of LC in patients with COPD of 25%7. The analysis was performed with SPSS 21.0 (IBM Corporation, Armonk, New York). CECILIA MOURONTE ROIBÁS 128 Results We included 280 patients: 109 cases (LC+COPD), 83 controls (COPD) and 88 LC patients. A descriptive and univariate analysis comparing baseline characteristics and marker levels of cases and controls is included in Table 2. Table 2. Univariate analysis comparing characteristics of cases and controls. Cases (LC+COPD) Controls (COPD) p Baseline characteristics Gender (male), n (%) 95 (87.1) 65 (78.3) 0.07 Age, mean (SD) 67 (10.3) 64.6 (9.4) 0.10 BMI, mean (SD) 26.6 (4.2) 27.3 (4.5) 0.29 Laboral exposure, n (%) 43 (39.4) 25 (30.1) 0.31 Tobacco history, n (%) 109 (100) 82 (98.8) 0.43 Active smokers, n (%) 62 (56.9) 45 (54.2) 0.39 Pack - years, mean (SD) 49.5 (23.8) 47.5 (25) 0.61 Emphysema, n (%) 68 (62.4) 38 (45.8) 0.32 GOLD I - II, n (%) 87 (79.8) 66 (79.5) 0.55 GesEPOC A (%) 105 (96.3) 80 (96.4) 0.65 Bodex, mean (SD) 1 (1.5) 0.8 (1.2) 0.30 CAT, mean (SD) 10.6 (6.2) 9.7 (7.6) 0.69 FEV 1 (%), mean (SD) 69.1 (21.1) 71 (20.2) 0.55 DLCO (%), mean (SD) 68.1 (21) 70.4 (22.6) 0.58 Charlson index, mean (SD) 1.0 (1.5) 0.7 (1) 0.11 Statin consumption, n (%) 40 (36.7) 31 (37.3) 0.52 Inflammatory markers TNF - α (pg/ml), mean (SD) 14.7 (46.4) 9.3 (7.4) 0.25 IL - 6 (pg/ml), mean (SD) 10.7 (16.6) 6.2 (12.1) 0.05 IL - 8 (pg/ml), mean (SD) 29.6 (44.1) 19.2 (28.8) 0.07 Leukocytes (per µl), mean (SD) 10,004,4 (11,096.3) 7,706.1 (2,334) 0.04 Lymphocytes (per µL), mean (SD) 2,334 (1,987.4) 2,398.5 (965.7) 0.77 Neutrophils (per µl), mean (SD) 5,920 (2,469.1) 4,464.2 (2,136.7) <0.001 NLR, mean (SD) 3.1 (1.8) 2.1 (1.5) <0.001 Platelets (per µl), mean (SD) 295,114,1 (124,102.4) 243,402.4 (72,978.9) 0.001 MPV (fl), mean (SD) 8.4 (1.2) 8.9 (1) 0.003 PLR, mean (SD) 154 (86.6) 118.5 (72.1) 0.003 Fibrinogen (mg/dl), mean (SD) 461 (198.7) 392.5 (166.5) 0.07 A1AT (mg/dl), mean (SD) 174 (49.9) 136.8 (29.1) <0.001 IgE (kU/l), mean (SD) 155,7 (109.7) 177.8 (569.3) 0.78 CRP (mg/l), mean (SD) 22 (31.7) 6.1 (8.8) <0.001 Cholesterol (mg/dl), mean (SD) 178.3 (37.1) 201.8 (37.1) <0.001 Bilirrubin (mg/dl), mean (SD) 0.6 (0.3) 0.6 (0.2) 0.50 BMI: Body mass index; GOLD: Global Initiative for Obstructive Lung Disease; GesEPOC A: non exacerbators, according to the Spanish Guidelines of COPD; CAT: COPD Assessment Test; FEV1: forced expiratory volume in the first second; DLCO: carbon monoxide diffusion capacity; IL: interleukin; NLR: neutrophil/lymphocyte ratio; MPV: mean platelet volume; PLR: platelet/lymphocyte ratio; A1AT: alpha 1-antitripsin; IgE: E immunoglobulin, CRP: C reactive protein. As shown in the table, baseline characteristics of both groups were very homogeneous, with no relevant differences between groups, also in terms of baseline treatments. There were Predictive value of a series of inflammatory markers in COPD for LC diagnosis 129 no patients undertaking any growth factor. One case and two controls had A1AT<90 mg/dl. Five patients had cachexia, four were cases (one in the group with high cholesterol levels and three with medium cholesterol levels) and one was a control. Baseline characteristics of LC patients without COPD are included in Table 3. Table 3. Characteristics of patients with LC only. LC patients without COPD Gender (male), n (%) 63 (71.6) Age, mean (SD) 65.7 (10.9) BMI, mean (SD) 29.3 (5.3) Laboral exposure, n (%) 28 (33.7) Tobacco history, n (%) 73 (83) Active smokers, n (%) 39 (44.3) Pack - years, mean (SD) 40.3 (23.11) SCLC, n (%) 4 (4.9) Adenocarcinoma n(%) 42 (54.5) Squamous, n (%) 20 (25) Advanced stage at diagnosis, n (%) 41 (48.2) FEV 1 (%), mean (SD) 87 (20.8) DLCO (%), mean (SD) 82.2 (20.3) Charlson index, mean (SD) 2 (2.2) BMI: Body mass index; SCLC: small cell lung cancer; FEV1: forced expiratory volume in the first second; DLCO: carbon monoxide diffusion coefficient. The most frequent histological type was adenocarcinoma, in 84 cases (44.9%), followed by squamous (26.7%), undifferentiated (18.2%), small-cell LC (SCLC) (7%) and carcinoid (3.2%). Regarding tumour characteristics, when comparing LC+COPD with LC patients, we found that patients with LC without COPD had more adenocarcinomas (54.5% vs 38.4%; p=0.02), whereas patients with LC+COPD had more SCLC (17.8% vs 4.9%; p=0.006). There were no differences in stage at diagnosis. Figure 1 shows descriptive boxplots for all inflammatory markers in the three groups of patients. CECILIA MOURONTE ROIBÁS 130 Figure 1. Descriptive comparison between levels of biomarkers in the three groups of patients Predictive value of a series of inflammatory markers in COPD for LC diagnosis 131 CECILIA MOURONTE ROIBÁS 132 We developed a multivariate logistic regression model comparing cases and controls (Table 4). Table 4. Multivariate analysis comparing characteristics of cases and controls with variables stratified by terciles. OR: odds-ratio; 95%CI: confidence interval of a 95%; A1AT: alpha 1-antitripsin; a OR adjusted by age and gender; b OR adjusted by age, gender, alpha 1-antitripsin, cholesterol and neutrophils. High neutrophil and A1AT levels and low cholesterol levels were the only significant variables in the multivariate analysis. Therefore, those were the variables chosen for their stratification in terciles and their inclusion in the score. It can be observed that three variables are associated significantly with the probability of being a case: patients with LC+COPD had significantly higher levels of neutrophils [OR 4.90 (95%CI 1.60-14.94 for those in the highest tercile of neutrophils, p=0.005] and A1AT [OR 3.6 (95%CI 1.23-10.53), for those in the highest tercile of A1AT, p=0.019] and lower cholesterol levels [OR 2.91 (95%CI 1.08-7.85), for those in the lowest tercile of cholesterol, p=0.03] than COPD controls. The point scoring system shown in Table 5 was used to measure the magnitude of the association of each of the significant factors in the multivariate analysis with the odds of being a case, thus leading to the development of a risk score. Table 5. Point scoring system for predicting the risk of being a case. Characteristic Points assigned* High A1AT levels ( ≥167 mg/dl) 4 Low and medium cholesterol levels (<200 mg/dl) 3 Medium neutrophil levels ( ≥4007 and <5955 per µl) 3 High neutrophil levels ( ≥5955 per µl) 5 *A total point score for a given patient is obtained by summing all the points for each applicable characteristic. The points assigned to each predictor variable were based on coefficients obtained from the logistic-regression model adjusted for age, sex, alpha 1-antitripsin, cholesterol and neutrophils exposed in Table 4. Predictive value of a series of inflammatory markers in COPD for LC diagnosis 133 Performance and ROC curves of this risk score are presented on Figure 2 and Table 6. Based on our model and assuming a prevalence of 25% among COPD patients, we reached a sensitivity of 80%, with an optimal negative predictive value (NPV) of 90.7%7. Figure 2. ROC curve of the risk score. Table 6. Sensitivity, specificity and predictive values of the risk score. AUC (95%CI) Cut - off value S (%) Sp (%) PPV (%) NPV (%) Risk score* 0.78 (0.71 - 0.86) >3.5 points 80 65.1 43.5 90.7 * The points assigned to each predictor variable were based on coefficients obtained from the logisticregression model adjusted for age, sex, alpha 1-antitripsin, cholesterol and neutrophils; S: sensitivity; Sp: specificity; PPV: positive predictive value; NPV: negative predictive value, AUC: area under the curve; CI: confidence interval We repeated the univariate and multivariate analyses excluding patients with advanced LC stage, to minimize the effect of higher inflammation levels in this kind of tumours. We found that in local LC+COPD, A1AT was significantly higher than in COPD patients: OR 1.02 (1.001.03); p=0.03, with an AUC of 66.4 (Table 7). CECILIA MOURONTE ROIBÁS 134 Table 7. Analysis in patients with local LC. UNIVARIATE ANALYSIS Cases (localized LC+COPD) Controls (COPD) p Baseline characteristics Gender (male), n (%) 31 (83.7) 65 (78.3) 0.330 Age, mean (SD) 65.5 (12.9) 64.6 (9.4) 0.680 BMI, mean (SD) 27.7 (4.3) 27.3 (4.5) 0.510 Laboral exposure, n (%) 15 (40.5) 25 (30.1) 0.390 Tobacco history, n (%) 37 (100) 82 (98.8) 0.690 Active smokers, n (%) 20 (54.1) 45 (54.2) 0.340 Pack - years, mean (SD) 45.9 (24) 47.5 (25) 0.750 GOLD I - II, n (%) 5 (13.5) 66 (79.5) 0.260 GesEPOC A (%) 35 (94.6) 80 (96.4) 0.490 Bodex, mean (SD) 0.9 (1.50) 0.8 (1.2) 0.700 CAT, mean (SD) 8.5 (3) 9.7 (7.6) 0.570 FEV 1 (%), mean (SD) 71.6 (21.3) 71 (20.2) 0.880 DLCO(%),mean (SD) 72.6 (22) 70.4 (22.6) 0.660 Charlson index, mean (SD) 1.3 (1.9) 0,7 (1) 0.010 Inflammatory markers TNF - α (pg/ml), mean (SD) 11.6 (21) 9.3 (7.4) 0.530 IL - 6 (pg/ml), mean (SD) 6.5 (6.1) 6.2 (12.1) 0.850 IL - 8 (pg/ml), mean (SD) 22.1 (46.4) 19.2 (28.8) 0.740 Leukocytes (per µl), mean (SD) 8,880.9 (4,039.1) 7,706.1 (2,334) 0.110 Lymphocytes (per µL),mean (SD) 2,744.9 (3,190.1) 2,398.5 (965.7) 0.370 Neutrophils (per µl), mean (SD) 5,491.1 (2,324.7) 4,464.2 (2,136.7) 0.020 NLR, mean (SD) 2.9 (1.9) 2.1 (1.5) 0.030 Platelets (per µl), mean (SD) 273,594.6 (132,871.4) 243,402.4 (72,978.9) 0.270 MPV (fl), mean (SD) 8.4 (1.3) 8.9 (1) 0.040 PLR, mean (SD) 135 (76.3) 118.5 (72.1) 0.260 Fibrinogen (mg/dl), mean (SD) 395.3 (185.2) 392.5 (166.5) 0.950 A1AT (mg/dl), mean (SD) 157.9 (42.6) 136.8 (29.1) 0.030 IgE (kU/l), mean (SD) 176.5 (216.5) 177.8 (569.3) 0.990 CRP (mg/l), mean (SD) 14.7 (20.6) 6.1 (8.8) 0.009 Cholesterol (mg/dl), mean (SD) 180.1 (44.6) 201.8 (37.1) 0.010 Bilirrubin (mg/dl), mean (SD) 0.73 (0.50) 0.6 (0.2) 0.060 MULTIVARIATE ANALYSIS OR 95%CI p A1AT (mg/dl) 1.02 1.00 - 1.03 0.03 BMI: Body mass index; GOLD: Global Initiative for Obstructive Lung Disease; GesEPOC A: non exacerbators, according to the Spanish Guidelines of COPD; CAT: COPD Assessment Test; FEV1: forced expiratory volume in the first second; DLCO: carbon monoxide diffusion capacity; IL: interleukin; NLR: neutrophil/lymphocyte ratio; MPV: mean platelet volume; PLR: platelet/lymphocyte ratio; A1AT: alpha 1antitripsin; IgE: E immunoglobulin, CRP: C reactive protein. Discussion Our results suggest that a panel of 3 biomarkers out of a panel of 16, which are easy to assess, might be able to detect LC in patients presenting COPD. As we have previously stated, evidence suggests that COPD is a risk factor for developing LC7, and one of the underlying mechanisms described is inflammation. Chronic inflammation has long been associated with Predictive value of a series of inflammatory markers in COPD for LC diagnosis 135 carcinogenesis, contributing to 25% of all human cancers8. We have observed that neutrophils, A1AT and cholesterol are associated with the risk of LC in COPD patients, and if they are used combined, they might predict LC risk with an AUC close to 80 %. If confirmed in other studies, these results could be relevant since LC is frequent among COPD patients and their use might detect the disease in earlier stages predicting a better clinical outcome. Evidence suggests that COPD is a risk factor for developing LC7, and one of the underlying mechanisms described is inflammation. Chronic inflammation has long been associated with carcinogenesis, contributing to 25% of all human cancers8 and systemic inflammation has also been shown to be a relevant manifestation of COPD25. As previously exposed in Table 1, several markers have shown associations with both COPD and LC. Leukocytes, TNF-α, IL-6, IL-8, cholesterol, bilirubin and fibrinogen levels increase mortality in COPD patients, whereas white blood and platelet markers are associated with a risk of COPD exacerbations10,11,26-28. Also, elevated IgE levels can be found in COPD patients29. In addition, TNF-α, IL-6, IL-8, NLR, PLR, IgE have been associated with LC risk in healthy subjects, being IL-6, lymphocytes, neutrophils, NLR, platelets, PLR, fibrinogen, A1AT, CRP and bilirubin poor prognostic factors in LC patients11,14,30-32. According to our results (Figure 1), we found differences in marker levels in patients with LC+COPD, and even in LC patients without COPD, such as IL6, leukocytes, PLR, fibrinogen, neutrophils, NLR, platelets, A1AT and CRP. This may indicate that these markers seem to be more related to the existence of LC than to COPD itself. In the multivariate analysis we found that some markers were statistically associated with LC onset: higher levels of neutrophils and A1AT and lower cholesterol levels. Lymphocytes play a crucial role in the cell-mediated host immune response to tumors. Infiltration of tumors by lymphocytes correlates with better prognosis in some cancers, although disease progression is associated with high leukocyte and neutrophil count11. Neutrophils support angiogenesis by secreting proangiogenic factors or proteolytic activation of such factors. Also, they ensure the collection of epidermal growth factor (EGFR), transforming growth factor-β1 (TGFβ1), platelet-derived growth factors that contribute to tumorigenesis. Neutrophils contain both proand anti-tumor subpopulations11. Neutrophil counts are known to CHAPTER 9. DISCUSSION. Discussion 145 9.1.DISCUSSION: HYPOTHESIS AND METHODS The poor prognosis of LC, its high prevalence among patients with COPD and the evidence postulating COPD as a risk factor for LC development (3,12), make it necessary to develop strategies with a potential use in the early detection of LC in patients with COPD and/or emphysema. Therefore, it is essential to improve our knowledge of the interaction between LC and COPD, and also to establish whether there is any relationship between the type of pulmonary emphysema and the development of LC. In addition, this would have prognostic and therapeutic consequences and would even have implications on the implementation of screening strategies. However, until now, it is not recommended to carry out a general screening of LC, although it is true that there are more and more working groups evaluating this point (206,207). The reasons why LC screening has not started yet in our environment are the low positive predictive value of LC screening by CT, the important implications that false positives may have for patients, the possibility of overdiagnosing cases of LC, the risks of developing radiation-induced cancer, and the great economic and organizational impact that a CT screening of the entire smoking population would imply (208). That is why, so far, there is no consensus about its realization in Europe. Some international guidelines, such as the IASCL, the ACCP, the ASCO or the ATS (209) recommend the implementation of screening strategies, while the Spanish and European guidelines are more inclined to recommend strategies based on the early detection of LC. These guidelines place special emphasis on the role played by the LCRDU within a multidisciplinary approach, as well as case-management nurses, having both demonstrated their capacity to minimize the loss of LC cases, accelerating the times of diagnosis and also reducing the costs of the high number of patients who previously required hospital management (3,12). Recently, numerous studies have been published that seem to show the existence of a relationship between LC, COPD and emphysema (15,60,65). However, there are no studies focusing on the phenotypic and multidimensional characterization of cases of COPD with LC that can help us choose the most appropriate therapy and its prognosis. The possibility of a relationship between different types of emphysema and the existence of LC has not been studied either. Similarly, there is little evidence about the role of some markers of inflammation in blood, which could serve as tools for early diagnosis, possible LC screening, severity assessment, evaluation of therapeutic response and/or taking diagnostic and therapeutic CECILIA MOURONTE ROIBÁS 146 decisions in the subgroup of patients with COPD. As a result of the limited information available on the relationship between these entities, this research project was carried out. The aim of this thesis is to estimate COPD prevalence and its degree of underdiagnosis in patients with LC, as well as to evaluate the clinical profile of patients with COPD and LC comparing it with another control group of patients with COPD without LC, to analyze its phenotypic, radiological and multidimensional characterization, considering the little existing literature and its discrepant results. With this purpose, several studies were designed. Initially, a systematic review of the evidence available to date was conducted. Subsequently, a prospective cohort study was designed for descriptive purposes of the frequency and phenotypic characteristics of patients synchronously diagnosed with COPD and LC, followed by two observational case-control studies, in which the cases were patients with COPD and LC, and controls, patients with COPD without LC. The cohort study was designed with the objective of establishing the prevalence and underdiagnosis of COPD in patients with LC, due to the high underdiagnosis of COPD in the general population. For this same reason and based on the need to have a CT for all patients with COPD, the second and third studies presented a case-control design, because it would have been very long and complex to conduct a cohort study designed to establish a relationship between the type of emphysema and the development of LC, or to study the role of different biomarkers by subgroups. The fact that the initial cohort study was multicentric has allowed to reach a large sample size, therefore including a representative sample of the resident population in the geographical area in which the research was developed, given that the entire Galician population has access to public healthcare coverage, which allows recruiting more than 95% of the total LC of the respective health areas. 9.2.DISCUSSION: RESULTS The first cohort study included 602 patients with LC, 310 with LC and COPD and 292 LC without COPD. The second case-control study included 243 patients, 169 with LC and COPD and 74 with COPD without LC. The third study included 280 patients, 109 cases with LC and COPD, 83 controls with COPD and 88 cases of LC without associated COPD. Discussion 147 Most patients included in the studies were male. As explained in the introduction, over the last decades, the male/female ratio of LC has been evolving from 10/1 to approximately 4/1 at present, mainly due to the incorporation of women into tobacco consumption (16,17). In the LC and COPD group, 88.7% of the cases were male, with a 7/1 ratio. This is explained not only by the existence of LC, but also of COPD, since it is a disease that affects mostly men (41). In the LC group without COPD, the ratio was 2/1, lower levels than those described for LC in the general population, which could be explained by a higher proportion of women within the group of non-smokers, who are mostly in the group that does not suffer from COPD (16,17). The mean age of our patients (67 years) is slightly lower than that described for LC in the literature (3), although it is true that the subgroup of patients with LC and COPD has almost the same age. Perhaps the age described in the literature is interfered by the presence of COPD, since, if we assume that COPD is a risk factor for the development of LC, it would require a latency period prior to the diagnosis of the neoplasm. This would explain the fact that patients with LC without COPD are younger. As described in the literature, most LC diagnoses are performed in advanced stages, which implies a low survival at 5 years. In our work, LC diagnosis (with or without associated COPD) was performed in advanced stages in more than half of the cases, without significant differences between having a concomitant COPD or not. Because the follow-up time of our cohort study was low (2 years), we could not draw definitive conclusions about the implications of this fact on survival. However, we did observe that the median survival of patients with LC without COPD was 37% higher than that of LC patients with COPD, although not significantly. However, both survival medians were quite low (22 and 16 months respectively). COPD prevalence among patients with LC was 51.5%, with a previous diagnosis of COPD in 28.4% cases. This shows that COPD is a common comorbidity among patients with LC, showing similar data to other studies available in the literature (56,210,211). The high percentage of COPD underdiagnosis is striking: 71.6%, which shows similar levels to those found in the general population. This means that, despite the availability of national and international guidelines, COPD remains an entity with a high degree of underdiagnosis, also in patients with LC. This may mean a worse response to treatment in patients with LC and COPD, due to delays in diagnosis and the influence of COPD when conditioning the evolution and therapeutic options in these patients (5). CECILIA MOURONTE ROIBÁS 148 As previously discussed, tobacco is the main risk factor for developing COPD, emphysema and LC (81,177). Practically all (98%) patients with COPD (with or without LC) had some type of previous exposure to tobacco, being almost half of them active smokers. These results were expected, since smoking is practically a necessary condition to diagnose a patient with COPD, except in those cases with other types of exposures (in our case, exposure to biomass smoke). More than 70% of patients with LC without COPD had presented some type of exposure to tobacco smoke, with 45.7% of cases still being active smokers. This clearly supports the evidence that postulates smoking as the main risk factor for both diseases. In both studies, patients were frequently mild COPD and were non-exacerbators (in the cohort study, 73.9% were GOLD I-II and 76.9% GOLD A-B, with a 90.3% of nonexacerbators; that, in the case-control study, 69.8% were GOLD I-II and 90% GOLD A-B, with a 90.1% of non-exacerbators). These data are relevant, because this is the group of patients with COPD that we are most interested in characterizing, given that their functional situation may allow them to benefit from diagnostic strategies, extension evaluation and more aggressive therapies against their oncological pathology. In addition, there is evidence that the risk of developing LC and dying from it is greater in patients with COPD GOLD I-II, while patients with more advanced COPD are more likely to die from COPD itself (5) . Adenocarcinoma was the most frequent histological type overall in all the studies included in this thesis. This may be related to several factors, such as changes in the characteristics of cigarettes (with filter and low nicotine), changes in the classification of adenocarcinoma (currently classified as adenocarcinoma to bronchiole-alveolar carcinoma), the increase in casual diagnoses (since adenocarcinoma is a more peripheral tumor and takes longer to produce symptoms) and the increase in women with LC, due to their greater susceptibility to develop malignancy after genetic, hormonal, and mutational factors, with a higher risk of having EGFR mutations (17-20). The subgroup of patients with LC and COPD had more frequently squamous cell carcinoma and SCLC, when compared with patients with LC but without COPD. In addition, we found that squamous carcinoma was the most frequent diagnosis in localized stages, while in advanced stages the most frequent histological type was SCLC. These data are similar to those available in the literature (22,212,213). Both histological types have been associated with smoking, more frequently than in the case of adenocarcinoma. In addition, the presence of Discussion 149 squamous cell carcinoma was more significantly associated with the presence of emphysema, and in our series, patients with LC and concomitant COPD had a lower DLCO, which could indicate the existence of an associated emphysema and thus relate to a higher prevalence of squamous carcinoma (162). Patients with LC and COPD had more comorbidities measured by the Charlson index than patients with LC without COPD, which could be explained by several factors. Cases with LC and COPD had a higher prevalence of smoking, which could imply the presence of chronic inflammatory processes that would lead to the development of a greater variety of comorbidities. In addition, it is known that apart from systemic inflammation, there are other mechanisms that may influence the coexistence of COPD with other cardiac and metabolic comorbidities, such as cellular senescence or telomeric shortening (28,29,214-217). Patients with LC and COPD were older and thinner than patients with COPD without LC. The higher age could be due to the latency time necessary for COPD to lead to the development of LC, while a lower BMI could be related to the fact that the majority of cases were nonexacerbating patients with emphysema. As previously explained, the available evidence about the association between the presence of emphysema and the development of LC is weak, especially given the disparity of results published to date, although it does seem clear that the evaluation by specialized radiologists of the existence of emphysema can be better correlated with the development of LC than its detection by automatic systems (60,65,179). In this work, we did not find a significant association between the existence of emphysema (considering all the subtypes together) and the presence of LC, despite having performed the evaluation of this emphysema in a semiquantitative manner by four experienced radiologists. However, in the literature available to date, there are no data that separately analyze the different types of emphysema, which could mean that the distribution between forms of emphysema within each study is heterogeneous and that this may therefore contribute to the disparity of the results. As explained below, an association between a specific subtype of emphysema and the presence of LC was found in this project. The second study focused on analyzing the existence of a relationship between a specific type of emphysema and the existence of LC. An association was observed between paraseptal CECILIA MOURONTE ROIBÁS 150 emphysema (alone or combined) and the presence of LC in patients with COPD. It is known that paraseptal emphysema affects predominantly upper lobes (185,186), something that is also observed in the present work. It is associated with male sex, an older age and the existence of interstitial pathology as well (162,186). In fact, it is the most common type of emphysema found in the association of emphysema and fibrosis (162,186). It is a type of emphysema that is not usually clinically relevant until it is in advanced stages, having not demonstrated a relationship with the development of symptoms in COPD, nor with the degree of airflow obstruction, nor with smoking history (162,187). In the emphysema study, a subgroup analysis was performed comparing the characteristics of patients with paraseptal emphysema with those of the other types of emphysema, finding a higher prevalence of adenocarcinoma, which could be related to the fact that it is a peripheral tumor that, as in the case of paraseptal emphysema, presents later clinical manifestations (2). De Torres et al. (80), described a scale (the COPD-LUCSS-DLCO), designed to help identify those patients with a high risk of developing LC. It is a scale that divides patients into two risk groups based on a score obtained from the combination of their age, BMI, smoking status and DLCO. In the study by De Torres, patients in the high-risk group were 2.4 times more likely to die than patients in the low-risk group. In the present project, 78.2% of the patients with LC and COPD would have been assigned to the high-risk group according to this scale, compared to 57.1% of patients with COPD without LC. However, this scale still needs to be validated. In the third study, a 16-biomarker panel was analyzed in three groups of patients: COPD, LC and LC with concomitant COPD. The results of this study show that patients with COPD who also have LC have higher levels of neutrophils and A1AT and lower cholesterol levels. Neutrophils promote angiogenesis by secreting proangiogenic factors. In addition, they intervene in the routes of EGFR, transforming growth factor-β1 (TGF-β1) and growth factors derived from platelets, thus contributing to tumor genesis (218). It is known that neutrophil counts are independent indicators of poor prognosis in patients with LC, whereas low neutrophil counts are associated with longer survival (195). Most of the data that relate the A1AT protein to COPD or LC are focused on its deficit (121). However, its role as an inflammatory marker when it is elevated has not been studied in this context. On the other hand, although more studies are needed to establish if there is an Discussion 151 association between A1AT and LC risk, there is evidence that A1AT promotes metastasis of lung adenocarcinoma (197). Although hyperlipidemia is a poor prognostic factor in patients with stomach and prostate cancer, there are few studies evaluating its role in LC. In this work (218), HDL, LDL and total cholesterol levels were lower in patients with LC compared with healthy controls, although only HDL levels were statistically significant. In the study of biomarkers, a risk scale was also developed to predict which patients with COPD had a higher risk of belonging to the group of cases (patients with COPD and LC), achieving high sensitivity and NPV. In fact, the area under the curve is close to 0.80 and, therefore, only 20% of patients using this score would be classified incorrectly. Therefore, A1AT, neutrophils and cholesterol are presented as parameters with potential diagnostic utility in the study of a possible LC in patients with COPD. However, although these are sensitive markers, they are not specific to COPD or LC, so our findings provide the basis for further studies that allow us to select those subjects with COPD who are more likely to benefit from screening by CT, as well as being able to select nodules with a higher risk of being malignant. 9.3.ADVANTAGES OF THIS THESIS This thesis started with a systematic review, which involved an exhaustive search of available literature on the relationship between COPD, emphysema and LC, which minimized the loss of relevant results. This review, published in a first-quartile journal, showed that both COPD and emphysema increase the risk of LC, with a dose-response association with tobacco. In addition, the results show that COPD is a highly underdiagnosed disease among patients with LC. After the systematic review, three studies were carried out, one of cohorts and two of cases and controls, with the main novelty that previously there were few data about the clinical and functional characteristics of patients with LC and COPD, as well as null information about the comorbidities that this group of patients usually presents. A total of 956 patients were included, which implies a reasonably large sample size, and the fact that the public health system is universal in our country, and that the Pneumology services of Vigo and Ourense have a LCRDU that evaluates the 95 % of all LCs in both health areas, has minimized the loss of cases and thus obtain a sufficiently representative sample of the southern area of Galicia. On the other hand, the diagnosis of COPD was made based on clinical and spirometric criteria in all cases, in accordance with the recommendations of current national and international guidelines (29,42), Conclusions 159 1. According to the literature analyzed in our systematic review, both COPD and emphysema increase the risk of developing LC, being this risk higher for smokers and increasing with higher tobacco consumption. These entities share several underlying etiopathogenic mechanisms. 2. In the multicenter cohort study, it was found that COPD is a highly underdiagnosed disease, also among patients with LC. The analyzes carried out in this work and in the systematic review emphasize the need to perform spirometry in active and former smokers, as well as imaging tests, in order to diagnose COPD and emphysema correctly and early, thus being able to select patients with an increased risk of developing LC. 3. Patients with LC and COPD present more squamous cell carcinomas and lower DLCO than patients with LC without COPD. This suggests a relationship between squamous cell carcinoma, smoking and the presence of emphysema. 4. Patients with LC and COPD have more comorbidities than LC patients without COPD, which could be related to the high prevalence of smoking in these patients, in addition to COPD itself. 5. Paraseptal emphysema in patients with COPD is more frequent in those cases that also have LC. In addition, patients with paraseptal emphysema have a higher proportion of adenocarcinoma cases than other types of emphysema. Therefore, patients with COPD and paraseptal emphysema could be a risk group for LC development, especially adenocarcinoma. 6. Patients with COPD who also have LC have higher levels of A1AT and neutrophils and lower cholesterol levels. These markers seem to be more related to the presence of LC than to COPD itself, since they are increased in patients with LC without COPD. On the other hand, in patients with LC and COPD at localized stage, A1AT is still significantly higher. In addition, the combination of A1AT, neutrophils and cholesterol presents a high sensitivity and NPV, so it may be a useful tool to identify patients with LC and COPD. However, although they are sensitive, these markers are not LC specific, and more studies are needed CECILIA MOURONTE ROIBÁS 160 so that these biomarkers can be used in clinical practice in order to select those subjects with COPD who are more likely to benefit from CT screening, or to select those nodules or other lesions with higher risk of malignancy. REFERENCES. References 165 1. Siegel R, Ma J, Zou Z, Jemal A. Cancer statistics, 2014. CA Cancer J Clin. 2014;64:9– 29. 2. Brambilla E, Travis WD. Lung Cancer. In: World Cancer Report, Stewart BW, Wild CP (Eds), World Health Organization, Lyon 2014. 3. National Cancer Institute. Surveillance, Epidemiology, and End Results Program. Cancer Stat Facts: Cancer of the Lung and Bronchus. Available at: https://seer.cancer.gov/statfacts/html/lungb.html; 2013 [Consulted 16.10.18]. 4. Lung Cancer. Spanish Society of Medical Oncology; 2017. Available at: https://seom.org/info-sobre-el-cancer/cancer-de-pulmon. [Consulted 16.10.18]. 5. Álvarez FV, Trueba IM, Sanchis JB, López-Rodó LM, Rodríguez Suárez PM, de Cos Escuín JS, et al. Recommendations of the Spanish Society of Pneumology and Thoracic Surgery on the diagnosis and treatment of non-small-cell lung cancer. Arch Bronconeumol. 2016;52(Suppl 1):2–62. 6. Ferlay J, Ervik M, Lam F, Colombet M, Mery L, Piñeros M, Znaor A, Soerjomataram I, Bray F (2018). Global Cancer Observatory: Cancer Today. Lyon, France: International Agency for Research on Cancer. Available from: https://gco.iarc.fr/today, accessed [20.02.19]. 7. Spanish Association Against Cancer: Lung Cancer. Available at: https://www.aecc.es/SobreElCancer/CancerPorLocalizacion/cancerdepulmon/Paginas/cancerd epulmon.aspx; 2017 [Consulted 16.10.18]. 8. REDECAN: Spanish Network of Cancer Registries. Madrid: REDECAN; 2017 Available at: http://redecan.org/es/index.cfm. [Consulted 03.11.2017]. 9. Álvaro Álvarez D, Bilbao-Goyoaga Arenas T, Quilez Ruiz-Rico N. Epidemiology, Ethiopathogenics and lung cancer biology. In: Broncogenic Carcinoma Update. Madrid: Ergón; 2012. (Monografías Neumomadrid; vol. XIX). 10. De Angelis R, Sant M, Coleman MP, Francisci S, Baili P, Pierannunzio D, et al. Cancer survival in Europe 1999-2007 by country and age: results of EUROCARE-5-a population-based study. Lancet Oncol. 2014;15:23–34. 11. Allemani C, Matsuda T, Di Carlo V, Harewood R, Matz M, Niksic M, et al. Global surveillance of trends in cancer survival 2000-14 (CONCORD-3): analysis of individual records for 37 513 025 patients diagnosed with one of 18 cancers from 322 population-based registries in 71 countries. Lancet. 2018;391:1023-75. CECILIA MOURONTE ROIBÁS 166 12. Leiro-Fernández V, Mouronte-Roibás C, Ramos-Hernández C, Botana-Rial M, González-Piñeiro A, García-Rodríguez E, et al. Changes in clinical presentation and staging of lung cancer over two decades. Arch Bronconeumol. 2014;50:417–21. 13. National Statistics Institute. National Survey of Health. Available at: http://www.ine.es/dyngs/INEbase/es/operacion.htm?c=Estadistica_C&cid=1254736176783& menu=resultados&idp=1254735573175; 2016 [Consulted 16.10.18]. 14. ISCIII: National Center of Epidemiology of the Carlos III Health Institute. Madrid; 2017. Available at: http://www.isciii.es/-unidades/centro-nacional-de-epidemiologia.shtml. [Consulted 16.10.18]. 15. Young RP, Hopkins RJ, Christmas T, Black PN, Metcalf P, Gamble GD. COPD prevalence is increased in lung cancer, independent of age, sex and smoking history. Eur Respir J. 2009;34:380–6. 16. Ruano-Ravina A, Figueiras A., Barros-Dios JM. Lung Cancer and related risk factors: an update of the literature. Public Health. 2003;117:149–56. 17. Hecht SS. Tobacco smoke carcinogens and lung cancer. J Natl Cancer Inst. 1999;91:1194–210. 18. Travis WD, Brambilla E, Noguchi M, Nicholson AG, Geisinger KR, Yatabe Y, et al. International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma. J Thorac Oncol. 2011;6:244–85. 19. Travis WD, Brambilla E, Riely GJ. New pathologic classification of lung cancer: relevance for clinical practice and clinical trials. J Clin Oncol. 2013;31:992–1001. 20. Burns DM, Anderson CM, Gray N. Do changes in cigarette design influence the rise in adenocarcinoma of the lung? Cancer Causes Control. 2011;22:13–22. 21. Nana-Sinkam SP, Powell CA. Molecular biology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: american college of chest physicians evidence-based clinical practice guidelines. Chest. 2013;143(5_suppl):e30S – e39S. 22. Huang R, Wei Y, Hung RJ, Liu G, Su L, Zhang R, et al. Associated Links Among Smoking, Chronic Obstructive Pulmonary Disease, and Small Cell Lung Cancer: A Pooled Analysis in the International Lung Cancer Consortium. EBioMedicine. 2015;2:1677–85. 23. Piotrowska Z, Sequist LV. Epidermal Growth Factor Receptor-Mutant Lung Cancer: New Drugs, New Resistance Mechanisms, and Future Treatment Options. Cancer J Sudbury Mass. 2015;21:371–7. References 167 24. Spira A, Halmos B, Powell CA. Update in Lung Cancer 2015. Am J Respir Crit Care Med. 2016;194:661–71. 25. Ofiara LM, Navasakulpong A, Beaudoin S, Gonzalez AV. Optimizing tissue sampling for the diagnosis, subtyping, and molecular analysis of lung cancer. Front Oncol. 2014;4:253. 26. García-Campelo R, Bernabé R, Cobo M, Corral J, Coves J, Dómine M, et al. SEOM clinical guidelines for the treatment of non-small cell lung cancer (NSCLC) 2015. Clin Transl Oncol. 2015;17:1020–9. 27. Detterbeck FC, Boffa DJ, Kim AW, Tanoue LT. The Eighth Edition Lung Cancer Stage Classification. Chest. 2017;151:193–203. 28. Grupo de Trabajo de GesEPOC. Clinical Practice Guidelines for the Diagnosis and Treatment of Patients with Chronic Obstructive Pulmonary Disease (COPD) - Spanish COPD Guidelines (GesEPOC).2017;53(Suppl 1):1–64. 29. Vogelmeier CF, Criner GJ, Martinez FJ, Anzueto A, Barnes PJ, Bourbeau J, et al. Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease 2017 Report. GOLD Executive Summary. Am J Respir Crit Care Med. 2017;195:557–82. 30. Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, Ezzati M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380:2163–96. 31. GBD 2013 Mortality and Causes of Death Collaborators. Global, regional, and national age-sex specific all-cause and cause-specific mortality for 240 causes of death, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet. 2015;385:117–71. 32. Eisner MD, Anthonisen N, Coultas D, Kuenzli N, Perez-Padilla R, Postma D, et al. An official American Thoracic Society public policy statement: Novel risk factors and the global burden of chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2010;182:693– 718. 33. Salvi SS, Barnes PJ. Chronic obstructive pulmonary disease in non-smokers. Lancet. 2009;374:733–43. 34. Mathers CD, Loncar D. Projections of global mortality and burden of disease from 2002 to 2030. PLoS Med. 2006;3:e442. 35. Halbert RJ, Natoli JL, Gano A, Badamgarav E, Buist AS, Mannino DM. Global burden of COPD: systematic review and meta-analysis. Eur Respir J. 2006;28:523–32. 36. Buist AS, McBurnie MA, Vollmer WM, Gillespie S, Burney P, Mannino DM, et al. International variation in the prevalence of COPD (the BOLD Study): a population-based prevalence study. Lancet. 2007;370:741–50. CECILIA MOURONTE ROIBÁS 174 107. Barbosa-Lorenzo R, Ruano-Ravina A, Ramis R, Aragonés N, Kelsey KT, CarballeiraRoca C, et al. Residential radon and COPD. An ecological study in Galicia, Spain. Int J Radiat Biol. 2017;93:222–30. 108. Kauppinen T, Toikkanen J, Pedersen D, Young R, Ahrens W, Boffetta P, et al. Occupational exposure to carcinogens in the European Union. Occup Environ Med. 2000;57:10–8. 109. Driscoll T, Nelson DI, Steenland K, Leigh J, Concha-Barrientos M, Fingerhut M, et al. The global burden of disease due to occupational carcinogens. Am J Ind Med. 2005;48:419– 31. 110. Pérez-Ríos M, Ruano-Ravina A, Etminan M, Takkouche B. A meta-analysis on wood dust exposure and risk of asthma. Allergy. 2010;65:467–73. 111. Dosil-Díaz O, Ruano-Ravina A, Gestal-Otero JJ, Barros-Dios JM. Meat and fish consumption and risk of lung cancer: A case-control study in Galicia, Spain. Cancer Lett. 2007;252:115–22. 112. Ruano-Ravina A, Figueiras A, Dosil-Diaz O, Barreiro-Carracedo A, Barros-Dios JM. A population-based case-control study on fruit and vegetable intake and lung cancer: a paradox effect? Nutr Cancer. 2002;43:47–51. 113. Dosil-Díaz O, Ruano-Ravina A, Gestal-Otero JJ, Barros-Dios JM. Consumption of fruit and vegetables and risk of lung cancer: a case-control study in Galicia, Spain. Nutrition. 2008;24:407-13. 114. Ruano-Ravina A, Figueiras A, Barros-Dios JM. Type of wine and risk of lung cancer: a case-control study in Spain. Thorax. 2004;59:981–5. 115. García Lavandeira JA, Ruano-Ravina A, Kelsey KT, Torres-Durán M, Parente-Lamelas I, Leiro-Fernández V, et al. Alcohol consumption and lung cancer risk in never smokers: a pooled analysis of case-control studies. Eur J Public Health. 2018;28:521-527. 116. Varraso R, Fung TT, Hu FB, Willett W, Camargo CA. Prospective study of dietary patterns and chronic obstructive pulmonary disease among US men. Thorax. 2007;62:786–91. 117. Shaheen SO, Jameson KA, Syddall HE, Aihie Sayer A, Dennison EM, Cooper C, et al. The relationship of dietary patterns with adult lung function and COPD. Eur Respir J. 2010;36:277–84. 118. Kaluza J, Larsson SC, Orsini N, Linden A, Wolk A. Fruit and vegetable consumption and risk of COPD: a prospective cohort study of men. Thorax. 2017;72:500–9. 119. Sun Z, Yang P. Role of imbalance between neutrophil elastase and alpha 1-antitrypsin in cancer development and progression. Lancet Oncol. 2004;5:182–90. References 175 120. Vidal R, Blanco I, Casas F, Jardí R, Miravitlles M. Guidelines for the diagnosis and management of alpha-1 antitrypsin deficiency Arch Bronconeumol. 2006;42:645–59. 121. Köhnlein T, Welte T. Alpha-1 antitrypsin deficiency: pathogenesis, clinical presentation, diagnosis, and treatment. Am J Med. 2008;121:3–9. 122. Miravitlles M, Herr C, Ferrarotti I, Jardi R, Rodriguez-Frias F, Luisetti M, et al. Laboratory testing of individuals with severe alpha1-antitrypsin deficiency in three European centres. Eur Respir J. 2010;35:960–8. 123. Yang P, Wentzlaff KA, Katzmann JA, Marks RS, Allen MS, Lesnick TG, et al. Alpha1antitrypsin deficiency allele carriers among lung cancer patients. Cancer Epidemiol Biomark Prev Publ. 1999;8:461–5. 124. Yang P, Sun Z, Krowka MJ, Aubry M-C, Bamlet WR, Wampfler JA, et al. Alpha1antitrypsin deficiency carriers, tobacco smoke, chronic obstructive pulmonary disease, and lung cancer risk. Arch Intern Med. 2008;168:1097–103. 125. El-Akawi ZJ, Nusier MK, Zoughool FE. Relationship between alpha-1 antitrypsin deficient genotypes S and Z and lung cancer in Jordanian lung cancer patients. Saudi Med J. 2006;27:181–4. 126. Torres-Durán M, Ruano-Ravina A, Parente-Lamelas I, Abal-Arca J, Leiro-Fernández V, Montero-Martínez C, et al. Alpha-1 Antitrypsin Deficiency and Lung Cancer Risk: A CaseControl Study in Never-Smokers. J Thorac Oncol. 2015;10:1279–84. 127. US Environmental Protection Agency. A Citizen’s Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon. Washington, US Environmental Protection Agency, 2012. Available at: www.epa.gov/radon/pubs/citiguide.html. [Consulted 13.06.18]. 128. World Health Organization 2009. Handbook on Indoor Radon: a Public Health Perspective. 2009, Geneva:WHO. 129. Pérez-Ríos M, Barros-Dios JM, Montes-Martínez A, Ruano-Ravina A. Attributable mortality to radon exposure in Galicia, Spain. Is it necessary to act in the face of this health problem? BMC Public Health. 2010;10:256. 130. Darby S, Hill D, Deo H, Auvinen A, Barros-Dios JM, Baysson H, et al. Residential radon and lung cancer-detailed results of a collaborative analysis of individual data on 7148 persons with lung cancer and 14,208 persons without lung cancer from 13 epidemiologic studies in Europe. Scand J Work Environ Health. 2006;32(Suppl 1):1–83. 131. Krewski D, Lubin JH, Zielinski JM, Alavanja M, Catalan VS, Field RW, et al. Residential radon and risk of lung cancer: a combined analysis of 7 North American casecontrol studies. Epidemiol Camb Mass. 2005;16:137–45. CECILIA MOURONTE ROIBÁS 176 132. Torres-Durán M, Barros-Dios JM, Fernández-Villar A, Ruano-Ravina A. Residential radon and lung cancer in never smokers. A systematic review. Cancer Lett. 2014;345:21–6. 133. Barros-Dios JM, Ruano-Ravina A, Pérez-Ríos M, Castro-Bernárdez M, Abal-Arca J, Tojo-Castro M. Residential radon exposure, histologic types, and lung cancer risk. A casecontrol study in Galicia, Spain. Cancer Epidemiol Biomark Prev Publ. 2012;21:951–8. 134. Barros-Dios JM, Barreiro MA, Ruano-Ravina A, Figueiras A. Exposure to residential radon and lung cancer in Spain: a population-based case-control study. Am J Epidemiol. 2002;156:548–55. 135. Torres-Durán M, Ruano-Ravina A, Parente-Lamelas I, Leiro-Fernández V, Abal-Arca J, Montero-Martínez C, et al. Lung cancer in never-smokers: a case-control study in a radonprone area (Galicia, Spain). Eur Respir J. 2014;44:994–1001. 136. Schwartz AG, Yang P, Swanson GM. Familial risk of lung cancer among nonsmokers and their relatives. Am J Epidemiol. 1996;144:554–62. 137. Matakidou A, Eisen T, Houlston RS. Systematic review of the relationship between family history and lung cancer risk. Br J Cancer. 2005;93:825–33. 138. Garte S. The role of ethnicity in cancer susceptibility gene polymorphisms: the example of CYP1A1. Carcinogenesis. 1998;19:1329–32. 139. Gao Y, Zhang Q. Polymorphisms of the GSTM1 and CYP2D6 genes associated with susceptibility to lung cancer in Chinese. Mutat Res. 1999;444:441–9. 140. Fernandez-Salguero P, Hoffman SM, Cholerton S, Mohrenweiser H, Raunio H, Rautio A, et al. A genetic polymorphism in coumarin 7-hydroxylation: sequence of the human CYP2A genes and identification of variant CYP2A6 alleles. Am J Hum Genet. 1995;57:651–60. 141. London SJ, Daly AK, Leathart JB, Navidi WC, Idle JR. Lung cancer risk in relation to the CYP2C9*1/CYP2C9*2 genetic polymorphism among African-Americans and Caucasians in Los Angeles County, California. Pharmacogenetics. 1996;6:527–33. 142. Kato S, Shields PG, Caporaso NE, Sugimura H, Trivers GE, Tucker MA, et al. Analysis of cytochrome P450 2E1 genetic polymorphisms in relation to human lung cancer. Cancer Epidemiol Biomark Prev Publ. 1994;3:515–8. 143. Uematsu F, Ikawa S, Kikuchi H, Sagami I, Kanamaru R, Abe T, et al. Restriction fragment length polymorphism of the human CYP2E1 (cytochrome P450IIE1) gene and susceptibility to lung cancer: possible relevance to low smoking exposure. Pharmacogenetics. 1994;4:58–63. References 177 144. Ruano-Ravina A, Pereyra MF, Castro MT, Pérez-Ríos M, Abal-Arca J, Barros-Dios JM. Genetic susceptibility, residential radon, and lung cancer in a radon prone area. J Thorac Oncol Off Publ Int Assoc Study Lung Cancer. 2014;9:1073–80. 145. Mercado N, Ito K, Barnes PJ. Accelerated ageing of the lung in COPD: new concepts. Thorax. 2015;70:482–9. 145. Landis SH, Muellerova H, Mannino DM, Menezes AM, Han MK, van der Molen T, et al. Continuing to Confront COPD International Patient Survey: methods, COPD prevalence, and disease burden in 2012-2013. Int J Chron Obstruct Pulmon Dis. 2014;9:597–611. 147. Barker DJ, Godfrey KM, Fall C, Osmond C, Winter PD, Shaheen SO. Relation of birth weight and childhood respiratory infection to adult lung function and death from chronic obstructive airways disease. BMJ. 1991;303:671–5. 148. Todisco T, de Benedictis FM, Iannacci L, Baglioni S, Eslami A, Todisco E, et al. Mild prematurity and respiratory functions. Eur J Pediatr. 1993;152:55–8. 149. Lawlor DA, Ebrahim S, Davey Smith G. Association of birth weight with adult lung function: findings from the British Women’s Heart and Health Study and a meta-analysis. Thorax. 2005;60:851–8. 150. Beran D, Zar HJ, Perrin C, Menezes AM, Burney P, Forum of International Respiratory Societies working group collaboration. Burden of asthma and chronic obstructive pulmonary disease and access to essential medicines in low-income and middle-income countries. Lancet Respir Med. 2015;3:159–70. 151. Gershon AS, Warner L, Cascagnette P, Victor JC, To T. Lifetime risk of developing chronic obstructive pulmonary disease: a longitudinal population study. Lancet Lond Engl. 2011;378:991–6. 152. Silva GE, Sherrill DL, Guerra S, Barbee RA. Asthma as a risk factor for COPD in a longitudinal study. Chest. 2004;126:59–65. 153. Vonk JM, Jongepier H, Panhuysen CIM, Schouten JP, Bleecker ER, Postma DS. Risk factors associated with the presence of irreversible airflow limitation and reduced transfer coefficient in patients with asthma after 26 years of follow up. Thorax. 2003;58:322–7. 154. Rijcken B, Schouten JP, Weiss ST, Speizer FE, van der Lende R. The relationship of nonspecific bronchial responsiveness to respiratory symptoms in a random population sample. Am Rev Respir Dis. 1987;136:62–8. 155. Hospers JJ, Postma DS, Rijcken B, Weiss ST, Schouten JP. Histamine airway hyperresponsiveness and mortality from chronic obstructive pulmonary disease: a cohort study. Lancet. 2000;356:1313–7. CECILIA MOURONTE ROIBÁS 178 156. Tashkin DP, Altose MD, Connett JE, Kanner RE, Lee WW, Wise RA. Methacholine reactivity predicts changes in lung function over time in smokers with early chronic obstructive pulmonary disease. The Lung Health Study Research Group. Am J Respir Crit Care Med. 1996;153:1802–11. 157. De Marco R, Accordini S, Marcon A, Cerveri I, Antó JM, Gislason T, et al. Risk factors for chronic obstructive pulmonary disease in a European cohort of young adults. Am J Respir Crit Care Med. 2011;183:891–7. 158. Drummond MB, Kirk GD. HIV-associated obstructive lung diseases: insights and implications for the clinician. Lancet Respir Med. 2014;2:583–92. 159. Jordan TS, Spencer EM, Davies P. Tuberculosis, bronchiectasis and chronic airflow obstruction. Respirology. 2010;15:623–8. 160. Hashimoto N, Matsuzaki A, Okada Y, Imai N, Iwano S, Wakai K, et al. Clinical impact of prevalence and severity of COPD on the decision-making process for therapeutic management of lung cancer patients. BMC Pulm Med. 2014;14:14. 161. De Torres JP, Marín JM, Casanova C, Cote C, Carrizo S, Cordoba-Lanus E, et al. Lung cancer in patients with chronic obstructive pulmonary diseaseincidence and predicting factors. Am J Respir Crit Care Med. 2011;184:913–9. 162. Smith BM, Schwartzman K, Kovacina B, Taylor J, Kasymjanova G, Brandao G, et al. Lung cancer histologies associated with emphysema on computed tomography. Lung Cancer. 2012;76:61–6. 163. Lim J, Shin KM, Lee K, Lim JK, Kim HJ, Cho SH, et al. Relationship Between Emphysema Severity and the Location of Lung Cancer in Patients With Chronic Obstructive Lung Disease. AJR Am J Roentgenol. 2015;205:540–5. 164. Schiavon M, Marulli G, Nannini N, Pasello G, Lunardi F, Balestro E, et al. COPDrelated adenocarcinoma presents low aggressiveness morphological and molecular features compared to smoker tumours. Lung Cancer. 2014;86:311–7. 165. O’Byrne KJ, Dalgleish AG. Chronic immune activation and inflammation as the cause of malignancy. Br J Cancer. 2001;85:473–83. 166. Lawless MW, O’Byrne KJ, Gray SG. Targeting oxidative stress in cancer. Expert Opin Ther Targets. 2010;14:1225–45. 167. Sharma S, Kelly TK, Jones PA. Epigenetics in cancer. Carcinogenesis. 2010 ;31:27–36. 168. Barreiro E, Peinado VI, Galdiz JB, Ferrer E, Marin-Corral J, Sánchez F, et al. Cigarette smoke-induced oxidative stress: A role in chronic obstructive pulmonary disease skeletal muscle dysfunction. Am J Respir Crit Care Med. 2010;182:477–88. References 179 169. Fermoselle C, Rabinovich R, Ausín P, Puig-Vilanova E, Coronell C, Sanchez F, et al. Does oxidative stress modulate limb muscle atrophy in severe COPD patients? Eur Respir J. 2012;40:851–62. 170. Pignatelli B, Li CQ, Boffetta P, Chen Q, Ahrens W, Nyberg F, et al. Nitrated and oxidized plasma proteins in smokers and lung cancer patients. Cancer Res. 2001;61:778–84. 171. Masri FA, Comhair SAA, Koeck T, Xu W, Janocha A, Ghosh S, et al. Abnormalities in nitric oxide and its derivatives in lung cancer. Am J Respir Crit Care Med. 2005;172:597–605. 172. Sandri BJ, Kaplan A, Hodgson SW, Peterson M, Avdulov S, Higgins L, et al. Multiomic molecular profiling of lung cancer in COPD. Eur Respir J. 2018;52. 173. Pastor MD, Nogal A, Molina-Pinelo S, Meléndez R, Salinas A, González De la Peña M, et al. Identification of proteomic signatures associated with lung cancer and COPD. J Proteomics. 2013;89:227–37. 174. Wauters E, Janssens W, Vansteenkiste J, Decaluwé H, Heulens N, Thienpont B, et al. DNA methylation profiling of non-small cell lung cancer reveals a COPD-driven immunerelated signature. Thorax. 2015;70:1113–22. 175. Fujii T, Dracheva T, Player A, Chacko S, Clifford R, Strausberg RL, et al. A preliminary transcriptome map of non-small cell lung cancer. Cancer Res. 2002;62:3340–6. 176. Hohberger LA, Schroeder DR, Bartholmai BJ, Yang P, Wendt CH, Bitterman PB, et al. Correlation of regional emphysema and lung cancer: a lung tissue research consortium-based study. J Thorac Oncol. 2014;9:639–45. 177. Biswas A, Mehta HJ, Folch EE. Chronic obstructive pulmonary disease and lung cancer: inter-relationships. Curr Opin Pulm Med. 2018;24:152–60. 178. Turner MC, Chen Y, Krewski D, Calle EE, Thun MJ. Chronic obstructive pulmonary disease is associated with lung cancer mortality in a prospective study of never smokers. Am J Respir Crit Care Med. 2007;176:285–90. 179. Li Y, Swensen SJ, Karabekmez LG, Marks RS, Stoddard SM, Jiang R, et al. Effect of emphysema on lung cancer risk in smokers: a computed tomography-based assessment. Cancer Prev Res Phila Pa. 2011;4:43–50. 180. Zulueta JJ, Wisnivesky JP, Henschke CI, Yip R, Farooqi AO, McCauley DI, et al. Emphysema scores predict death from COPD and lung cancer. Chest. 2012;141:1216–23. 181. Fishman A, Martinez F, Naunheim K, Piantadosi S, Wise R, Ries A, et al. A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema. N Engl J Med. 2003;348:2059–73. CECILIA MOURONTE ROIBÁS 180 182. Leopold JG, Gough J. The centrilobular form of hypertrophic emphysema and its relation to chronic bronchitis. Thorax. 1957;12:219–35. 183. Pratt PC, Kilburn KH. A modern concept of the emphysemas based on correlations of structure and function. Hum Pathol. 1970;1:443–63. 184. Hansell DM, Bankier AA, MacMahon H, McLoud TC, Müller NL, Remy J. Fleischner Society: glossary of terms for thoracic imaging. Radiology. 2008;246:697–722. 185. Edge J, Simon G, Reid L. Peri-acinar (paraseptal) emphysema: its clinical, radiological, and physiological features. Br J Dis Chest. 1966;60:10–8. 186. Araki T, Nishino M, Zazueta OE, Gao W, Dupuis J, Okajima Y, et al. Paraseptal emphysema: Prevalence and distribution on CT and association with interstitial lung abnormalities. Eur J Radiol. 2015;84:1413–8. 187. Satoh K, Kobayashi T, Misao T, Hitani Y, Yamamoto Y, Nishiyama Y, et al. CT assessment of subtypes of pulmonary emphysema in smokers. Chest. 2001;120:725–9. 188. Sverzellati N, Lynch DA, Pistolesi M, Kauczor H-U, Grenier PA, Wilson C, et al. Physiologic and quantitative computed tomography differences between centrilobular and panlobular emphysema in COPD. Chronic Obstr Pulm Dis. 2014;1:125–32. 189. Bishawi M, Moore W, Bilfinger T. Severity of emphysema predicts location of lung cancer and 5-y survival of patients with stage I non-small cell lung cancer. J Surg Res. 2013;184:1–5. 190. Seijo LM, Zulueta JJ. Understanding the Links Between Lung Cancer, COPD, and Emphysema: A Key to More Effective Treatment and Screening. Oncol Williston Park N. 2017;31(2). 191. Ueda K, Jinbo M, Li TS, Yagi T, Suga K, Hamano K. Computed tomography-diagnosed emphysema, not airway obstruction, is associated with the prognostic outcome of early-stage lung cancer. Clin Cancer Res. 2006;12:6730-6. 192. Takiguchi Y, Sekine I, Iwasawa S, Kurimoto R, Tatsumi K. Chronic obstructive pulmonary disease as a risk factor for lung cancer. World J Clin Oncol. 2014;5:660–6. 193. Strange C. COPD and lung cancer: are they both airways diseases? Chest. 2010;138:1289-90. 194. Agustí A, Edwards LD, Rennard SI, MacNee W, Tal-Singer R, Miller BE, et al. Persistent systemic inflammation is associated with poor clinical outcomes in COPD: a novel phenotype. PloS One. 2012;7:e37483. 195. Czyżykowski R, Nowak D, Janiak A, Włodarczyk A, Sarniak A, Krakowska M, et al. A retrospective evaluation of associations between chronic obstructive pulmonary disease, References 181 smoking, and efficacy of chemotherapy and selected laboratory parameters in patients with advanced non-small cell lung cancer. Contemp Oncol Poznan Pol. 2016;20:407–13. 196. Barreiro E, Fermoselle C, Mateu-Jimenez M, Sánchez-Font A, Pijuan L, Gea J, et al. Oxidative stress and inflammation in the normal airways and blood of patients with lung cancer and COPD. Free Radic Biol Med. 2013;65:859–71. 197. Li Y, Miao L, Yu M, Shi M, Wang Y, Yang J, et al. α1-antitrypsin promotes lung adenocarcinoma metastasis through upregulating fibronectin expression. Int J Oncol. 2017;50:1955–64. 198. Jin J, Liu X, Sun Y. The prevalence of increased serum IgE and Aspergillus sensitization in patients with COPD and their association with symptoms and lung function. Respir Res. 2014;15:130. 199. Helby J, Bojesen SE, Nielsen SF, Nordestgaard BG. IgE and risk of cancer in 37 747 individuals from the general population. Ann Oncol Off J Eur Soc Med Oncol. 2015;26:1784– 90. 200. Agassandian M, Shurin GV, Ma Y, Shurin MR. C-reactive protein and lung diseases. Int J Biochem Cell Biol. 2014;53:77–88. 201. Budweiser S, Harlacher M, Pfeifer M, Jörres RA. Co-morbidities and hyperinflation are independent risk factors of all-cause mortality in very severe COPD. COPD. 2014;11:388–400. 202. Horsfall LJ, Rait G, Walters K, Swallow DM, Pereira SP, Nazareth I, et al. Serum bilirubin and risk of respiratory disease and death. JAMA. 2011;305:691–7. 203. Song Y-J, Gao X-H, Hong Y-Q, Wang L-X. Direct bilirubin levels are prognostic in non-small cell lung cancer. Oncotarget. 2017;9:892–900. 204. Rami-Porta R, Crowley JJ, Goldstraw P. The revised TNM staging system for lung cancer. Ann Thorac Cardiovasc Surg. 2009;15:4–9. 205. Muir K., Gomeni R. Non-compartmental analysis. In Pharmacokinetics in Drug Development: Clinical Study Design and Analyisis (ed. Bonate P.L., Howard D.R.) 235-266. (AAPS Press, Arlington, 2004). 206. Oudkerk M, Devaraj A, Vliegenthart R, Henzler T, Prosch H, Heussel CP, et al. European position statement on lung cancer screening. Lancet Oncol. 2017;18:e754–66. 207. Smith RA, Andrews KS, Brooks D, Fedewa SA, Manassaram-Baptiste D, Saslow D, et al. Cancer screening in the United States, 2017: A review of current American Cancer Society guidelines and current issues in cancer screening. CA Cancer J Clin. 2017;67:100–21. CECILIA MOURONTE ROIBÁS 182 208. Ruano-Ravina A, Pérez Ríos M, Fernández-Villar A. Cribado de cáncer de pulmón con tomografía computarizada de baja dosis después del National Lung Screening Trial. El debate continúa abierto. Arch Bronconeumol. 2013;49:158–65. 209. Wiener RS, Gould MK, Arenberg DA, Au DH, Fennig K, Lamb CR, et al. An official American Thoracic Society/American College of Chest Physicians policy statement: implementation of low-dose computed tomography lung cancer screening programs in clinical practice. Am J Respir Crit Care Med. 2015;192:881-91 210. Abal Arca J, Parente Lamelas I, Almazán Ortega R, Blanco Pérez J, Toubes Navarro ME, Marcos Velázquez P. Cáncer de pulmón y EPOC: una asociación frecuente. Arch Bronconeumol. 2009;45:502–7. 211. Qin J, Li G, Zhou J. Characteristics of elderly patients with COPD and newly diagnosed lung cancer, and factors associated with treatment decision. Int J Chron Obstruct Pulmon Dis. 2016;11:1515–20. 212. Rodríguez-Roisin R, Soriano JB. Chronic obstructive pulmonary disease with lung cancer and/or cardiovascular disease. Proc Am Thorac Soc. 2008;5:842–7. 213. Mohan A, Mohan C, Pathak AK, Pandey RM, Guleria R. Impact of chronic obstructive pulmonary disease on respiratory status and quality of life in newly diagnosed patients with lung cancer. Respirology. 2007;12:240–7. 214. Decramer M, Janssens W. Chronic obstructive pulmonary disease and comorbidities. Lancet Respir Med. 2013;1:73–83. 215. Islam KMM, Jiang X, Anggondowati T, Lin G, Ganti AK. Comorbidity and Survival in Lung Cancer Patients. Cancer Epidemiol Biomark Prev Publ. 2015;24:1079–85. 216. Grose D, Morrison DS, Devereux G, Jones R, Sharma D, Selby C, et al. Comorbidities in lung cancer: prevalence, severity and links with socioeconomic status and treatment. Postgrad Med J. 2014;90:305–10. 217. Iachina M, Jakobsen E, Møller H, Lüchtenborg M, Mellemgaard A, Krasnik M, et al. The effect of different comorbidities on survival of non-small cells lung cancer patients. Lung. 2015;193:291–7. References 183 218. Şahin F, Aslan AF. Relationship between Inflammatory and Biological Markers and Lung Cancer. J Clin Med. 2018;7. 219. Smith BM, Pinto L, Ezer N, Sverzellati N, Muro S, Schwartzman K. Emphysema detected on computed tomography and risk of lung cancer: a systematic review and metaanalysis. Lung Cancer Amst Neth. 2012;77:58–63