Serum CD26 is related to histopathological polyp traits and behaves as a marker for colorectal cancer and advanced adenomas

De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Open Access RESEARCH ARTICLE © 2010 De Chia a e al; licensee BioMed Cen al L d. This is an Open Access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License (h p://c ea i ecommons.o g/licenses/by/2.0), which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed. Resea ch a icle Se um CD26 is ela ed o his opa hological polyp ai s and beha es as a ma ke o colo ec al cance and ad anced adenomas Lo e a De Chia a †1 , Ana M Rod íguez-Piñei o †1 , F ancisco J Rod íguez-Be ocal 1 , Osca J Co de o 2 , Da id Ma ínez- A es 3 and Ma ía Páez de la Cadena* 1 Abs ac Backg ound: Se um CD26 (sCD26) le els we e p e iously ound diminished in colo ec al cance (CRC) pa ien s compa ed o heal hy dono s, sugges ing i s po en ial u ili y o ea ly diagnosis. The e o e we aimed o es ima e he u ili y o he sCD26 as a bioma ke o CRC and ad anced adenomas in a high- isk g oup o pa ien s. The ela ionship o his molecule wi h polyp cha ac e is ics was also add essed. Me hods: sCD26 le els we e measu ed by ELISA in 299 symp oma ic and asymp oma ic pa ien s who had unde gone a colonoscopy. Pa ien s we e diagnosed as ha ing no colo ec al pa hology, non-in lamma o y o in lamma o y bowel disease, polyps (hype plas ic, non-ad anced and ad anced adenomas) o CRC. Resul s: A a 460 ng/mL cu -o , he sCD26 has a sensi i i y and speci ici y o 81.8% (95% CI, 64.5-93.0%) and 72.3% (95% CI, 65.0-77.2%) o CRC ega ding no o benign colo ec al pa hology. Clinicopa hological analysis o polyps showed a ela ionship be ween he sCD26 and he g ade o dysplasia and he p esence o ad anced adenomas. Hence, a 58.0% (95% CI, 46.5-68.9%) sensi i i y de ec ing CRC and ad anced adenomas was ob ained, wi h a speci ici y o 75.5% (95% CI, 68.5-81.0%). Conclusions: Ou p elimina y esul s show ha measu emen o he sCD26 is a non-in asi e and easonably sensi i e assay, which could be combined wi h o he s such as he aecal occul blood es o he ea ly diagnosis and sc eening o CRC and ad anced adenomas. Addi ional compa a i e s udies in a e age- isk popula ions a e necessa y. Backg ound Colo ec al cance (CRC) is one o he ou mos p e alen cance s in Wes e n coun ies due o a low eco e y a e in ad anced s ages, when mic ome as ases may be al eady p esen . I de elops om p ecance ous lesions (adenomas) ha a e easily emo ed by polypec omy, a p ocedu e ha educes CRC incidence by 75-90% [1]; mo eo e , ea men o ea ly diagnosed umou s has a good p ognosis [2]. Fu he mo e, acco ding o he MIS- CAN-COLON simula ion model, a 23% educ ion in CRC mo ali y would be achie ed wi h he sc eening o a leas 70% o he a ge popula ion [3]. The e o e sc een- ing o CRC aims o educe mo ali y a es by de ec ion and emo al o ea ly-s age umou s, and incidence a es by iden i ica ion and esec ion o polyps [4]. The e is a g ea a ie y o me hods o he de ec ion o CRC. A e iew o he ongoing sc eening ini ia i es wo ld- wide was ecen ly published [5]. The la es Join Colo ec- al Cance Sc eening Guidelines [6] di ide he a ailable es s in o wo ca ego ies: hose p ima ily aimed o de ec cance (blood and DNA s ool es s), and hose di ec ed o de ec also ad anced lesions (endoscopic and adio- g aphic me hods). Wi hin he a ailable in asi e es s a e he lexible sig- moidoscopy, he double-con as ba ium enema and he colonoscopy. The la e is ecommended nowadays as he gold s anda d, hough i s miss a es ha e been es ima ed as 22% o adenomas and 2-6% o CRC [7]. Howe e , bowel p epa a ion cons i u es he mos objec ionable aspec o he p ocedu e, undamen al o a p ope * Co espondence: mpae[email p o ec ed] 1 Uni e sidad de Vigo. Facul ad de Biología. Depa amen o de Bioquímica, Gené ica e Inmunología. As Lagoas-Ma cosende s/n. 36310 Vigo, Spain † Con ibu ed equally Full lis o au ho in o ma ion is a ailable a he end o he a icle De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 2 o 9 sc eening colonoscopy [8]. O he limi a ions o he colonoscopy a e he isk o complica ions, he cos s, and access. Rega ding non-in asi e es s, he mos common me hod, nowadays ecommended o CRC sc eening, is he guaiac aecal occul blood es (gFOBT), wi h highly a iable and b and-dependen sensi i i ies and speci ici- ies [6,9] and equi ing die a y es ic ions. Thus he e is an impe a i e need o de eloping non- in asi e sc eening es s o he de ec ion o CRC and ade- nomas, and hence many cu en s udies a e e alua ing se um ma ke s. Examples o hese a e he α-de ensins [10], he nico inamide N-me hyl ans e ase [11], he α-L- ucosidase [12], o he colon cance -speci ic an igens (CCSA) -2, -3 and -4 [13,14]. A majo d awback in hese s udies is hey a e limi ed o disc imina ing be ween CRC pa ien s and heal hy indi iduals, lea ing aside p ecu so lesions and no including in he con ol coho indi idu- als wi h benign pa hologies. P e ious s udies o ou g oup de ec ed ha soluble se um CD26 (sCD26) le els we e diminished in CRC pa ien s as compa ed o heal hy dono s [15,16]. In hose s udies, a sCD26 cu -o o 410 ng/mL demons a ed a 90% diagnos ic e iciency, wi h a speci ici y and sensi i - i y o 90% as well [15]. This high diagnos ic e iciency, e en in ea ly umou s ages, sugges ed i s po en ial u ili y o diagnosis. Thus we conside ed o in e es o ex end he alida ion o he sCD26 as an ea ly bioma ke o CRC, including also p ecance ous lesions (adenomas). One o he no el ies o he s udy is he use o a colono- scopically heal hy coho ins ead o a blood dono coho as he con ol popula ion. Mo eo e , his is he i s ime he sCD26 is analyzed ega ding he clinicopa hological cha ac e is ics o colo ec al polyps. Thus, we aim o anal- yse he ela ionship o he se um CD26 le els wi h he colonoscopic indings, in o de o alida e he u ili y o his p o ein as a ma ke o CRC diagnosis. Me hods Popula ion The popula ion s udied consis ed o pa ien s om he CHUVI hospi al (Complejo Hospi ala io Uni e si a io de Vigo; Spain) who had unde gone colonoscopy a he Gas- oen e ology Depa men . All he p ocedu es desc ibed we e pe o med acco ding o he clinical e hical p ac ices o he Spanish Go e nmen . The s udy was app o ed by he Galician E hical Commi ee o Clinical Resea ch (2002/059) and complied wi h he ene s o he Helsinki Decla a ion, he O iedo Ag eemen , he O ganic Law o Da a P o ec ion 15/1999 and he Royal Dec ee 1720/ 2007. Anonymi y was wa an ed h ough he use o clini- cal his o y numbe s. Fo pa ien s willing o be included in he s udy, in o med consen was ob ained and blood was ex ac ed. The only exclusion c i e ion was a non-com- ple ed colonoscopy (unde s ood as comple ed when he caecum was eached). The 299 pa ien s included we e bo h males and emales, wi h ages anging om 18 o 93 yea s. Clinical his o ies we e eco ded, including symp- oms o bowel disease, pe sonal his o y o polyps, CRC and o he cance s, amily his o y o cance , and colonos- copy indica ion. This was mos ly due o symp oms as ec- al bleeding (35.5%), abdominal pain (10%), dia hoea (9%), cons ipa ion (5.7%), anaemia (5%), bu also o col- o ec al polyp (12.7%) o cance (4.3%) su eillance, o CRC sc eening (12.4%). All p ocedu es we e blinded. Based on he his ological epo , pa ien s we e classi- ied in o: no colo ec al pa hology, non-in lamma o y bowel disease (non-IBD), in lamma o y bowel disease (IBD), polyps and CRC; polyps we e sub-classi ied as hype plas ic o adenomas. Ad anced adenomas we e de ined as hose la ge han 10 mm, wi h ubulo illous o illous his ology, o wi h high-g ade dysplasia. Pa ien s wi h mo e han one polyp we e classi ied acco ding o he mos ad anced lesion. CRC pa ien s we e classi ied acco ding o Dukes' s aging. No ca cinomas in si u we e de ec ed in he pa ien s included in he s udy. Collec ion o blood samples and de e mina ion o he sCD26 le els Blood samples we e collec ed, coagula ed a oom em- pe a u e o 20 min, and cen i uged a 2,000 g 15 min. Se a we e s o ed a -80°C. The sCD26 concen a ion was measu ed wi h he sCD26 ELISA ki (Bende Medsys- ems; Vienna, Aus ia) acco ding o he manu ac u e 's ins uc ions. Colo ime ic quan i ica ion was pe o med wi h a mic opla e eade (model 550; Bio-Rad, USA) a 450/570 nm. S a is ical analysis S a is ical analyses we e pe o med wi h he SPSS pack- age ( 16.0); es s we e wo-sided; p- alues < 0.05 we e conside ed signi ican . No mal dis ibu ions and homo- genei y o a iances we e e i ied by Kolmogo o - Smi no and Le ene';s es s, espec i ely. Analysis o wo independen samples was done by Mann-Whi ney's U, whe eas o mo e samples we employed he K uskal-Wal- lis es . Chi-squa e o Fische 's exac es s we e done wi h con ingency ables, and applied o analyses ega ding posi i i y/nega i i y o he sCD26. Bon e oni, alse dis- co e y a e (FDR) and SGoF es s we e subsequen ly pe - o med wi h he SGoF me a es so wa e o co ec o mul iple compa ison [17]. The sCD26 abili y o sepa a e heal hy om diseased pa ien s was s udied by ecei e ope a ing cha ac e is ic (ROC) cu es. Sensi i i y and speci ici y we e calcula ed using MedCalc ( .10.0.2). De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 3 o 9 Resul s sCD26 le els acco ding o he colonoscopic esul s Acco ding o he colonoscopic diagnosis, he 299 pa ien s we e classi ied as 68 pa ien s wi h no colo ec al pa hol- ogy (symp oma ic wi h ec al bleeding, abdominal pain, dia hoea, anaemia, cons ipa ion, o asymp oma ic wi h pe sonal his o y o polyps o CRC, and amily his o y o polyps); 64 pa ien s wi h non-IBD (haemo hoids and di e icula); 26 pa ien s wi h IBD (coli is o C ohn's dis- ease); 108 pa ien s wi h colo ec al polyps (hype plas ic polyps, non-ad anced adenomas and ad anced ade- nomas); and 33 pa ien s wi h CRC. As shown in able 1, he a e age sCD26 le el o he 6 g oups wi h no colo ec al pa hology was 641.2 ± 241.2 ng/mL; indi iduals wi h anaemia showed a conside ably low sCD26 mean (370.8 ± 144.7 ng/mL), s a is ically di - e en om o he non-colo ec al pa hology pa ien s (U es p = 0.001). Rega ding pa ien s wi h colo ec al pa hol- ogy, he non-IBD g oup exhibi ed mean sCD26 le els simila o he non-colo ec al pa hology g oup (612.2 ± 231.0 ng/mL). In con as , pa ien s wi h IBD showed lowe alues wi h ela i ely mo e a ia ion (434.4 ± 239.7 ng/mL). Pa ien s diagnosed as ha ing polyps (bo h hype - plas ic and adenomas) esul ed in an in e media e mean sCD26 concen a ion (588.0 ± 246.5 ng/mL), while pa ien s wi h CRC egis e ed he lowes le els (403.7 ± 278.2 ng/mL). The Kolmogo o -Smi no es demons a ed, excep o he CRC popula ion (p = 0.035), a no mal dis ibu ion o he sCD26 concen a ion o all he g oups. When he le els o sCD26 we e compa ed among all he i e g oups o pa ien s, we ound signi ican di e ences (K uskal- Wallis es p < 0.001). Mo eo e , his di e ences we e no ela ed o gende (U es p = 0.219) o age (≤ 50 yea s o > 50 yea s; U es p = 0.109), as epo ed in a la ge coho s udy [18]. ROC cu e and sCD26 posi i i y To e alua e he u ili y o he sCD26 as a umou ma ke , we es ima ed a cu -o o di e en ia e he CRC g oup (33 pa ien s) om he con ol popula ion (68 pa ien s wi h no colo ec al pa hology). Fi s we cons uc ed he ROC cu e, which esul ed in an a ea o 0.811 (95% CI, 0.721- 0.882; p < 0.0001). On he basis o his plo , able 2 shows ou di e en po en ial cu -o alues wi h hei espec- i e sensi i i y and speci ici y. Sensi i i y o CRC almos eached 85% a he cu -o o 500 ng/mL, bu wi h a spec- i ici y below 75%; when speci ici y was aised up o 83.8% a 390 ng/mL, sensi i i y esul ed in a 57.6%. The cu -o alue wi h he highes a e age diagnos ic pe o mance was 460 ng/mL, showing a sensi i i y o 81.8% (95% CI, 64.5-93.0%) wi h a speci ici y o 79.4% (95% CI, 67.9- 88.3%). A posi i e sCD26 alue was he e o e ≤ 460 ng/mL ( ig- u e 1). The posi i i y a e inc eased om 20.6% (14/68) in he non-colo ec al pa hology g oup o 81.8% (27/33) in he CRC g oup. Pa ien s wi h non-IBD, IBD, hype plas ic polyps, non-ad anced adenomas and ad anced ade- nomas showed in e media e a es, co esponding o 28.1% (18/64), 69.2% (18/26), 22.2% (4/18), 22.5% (9/40) and 41.7% (20/48), espec i ely. Rela ionship be ween he sCD26 and he clinicopa hological ea u es o polyps We analysed he ela ionship o he sCD26 wi h he his o- pa hological cha ac e is ics o he colo ec al polyps ound by colonoscopy ( able 3), including: numbe o pol- yps (1-2, 3 o mo e); size (≤ 0.5 cm, 0.6-1 cm, > 1 cm); loca ion ( ec um, sigma, le colon, ans e se colon, igh colon); mo phology (sessile, pedicula ed, la ); his ology (hype plasic, adenoma) and de ailed his ology (hype - plas ic, ubula , illous, ubulo illous); g ade o dysplasia (absence, low-g ade, high-g ade); and p esence o ad anced adenomas. The his ology o wo polyps was missing. The a iables gende and age (≤ 50 and >50 yea s) we e also s udied, con i ming no s a is ical di e - ences in ela ion o he sCD26 posi i i y (p = 0.212 and p = 0.132, espec i ely). The Chi-squa e es s e ealed no s a is ical di e ences ega ding he numbe o polyps, hei size, loca ion, mo - phology o his ology. Di e ences close o signi ican we e obse ed be ween he sCD26 posi i i y and he g ade o dysplasia (p = 0.056). The posi i i y a e inc eased g adu- ally while he deg ee o dysplasia became mo e se e e: 22.2% o non-dysplas ic polyps, 32.5% o low-g ade dys- plas ic adenomas and almos double (60.0%) o high- g ade dysplas ic adenomas. When compa ing he sCD26 posi i i y a e o he ad anced and non-ad anced ade- nomas popula ions, s a is ically signi ican di e ences we e de ec ed (p = 0.048). Bon e oni, FDR and SGoF pos -hoc es s we e no signi ican o any o hese analy- ses. Finally, diagnos ic pa ame e s we e calcula ed o he de ec ion o ad anced adenomas and CRC, wi h he con- ol g oup including all he emaining coho s ( able 4). A he 460 ng/mL cu -o , sensi i i y esul ed in 58.0% (95% CI, 46.5-68.9%), wi h a speci ici y o 75.5% (95% CI, 68.5-81.0%). When hese pa ame e s we e calcula ed o he de ec ion o only CRC pa ien s, he sensi i i y inc eased o 81.8% (95% CI, 64.5-93.0%) whe eas he speci ici y was jus sligh ly diminished o 72.3% (95% CI, 65.0-77.2%). This alue inc eased o 90% (95% CI, 73.4- 97.8%) i he speci ici y was calcula ed o he non-symp- oma ic g oup e sus he CRC g oup. Discussion The glycop o ein CD26 o dipep idyl pep idase IV (DPPIV, E.C. 3.4.14.5) is an exopep idase o he plasma memb ane able o elease dipep ides om he N- e minal end o pep ides/p o eins bea ing p oline o alanine in he De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 4 o 9 penul ima e posi ion [19]. Biological luids con ain ela- i ely high le els o sCD26, which is p esumably shed by p o eoly ic clea age om any cell exp essing ansmem- b ane CD26 [20]. Al hough i s o igin is s ill unclea , he li e and he T cells a e ci ed as he mos likely sou ces [21]. The measu emen o he sCD26 le els was pe o med in se um om indi iduals whom, due o di e en medical indica ions, had unde gone colonoscopy; mos o hem e e ed abdominal, colon o ec al symp oms, o amil- ial/pe sonal his o y o polyps o CCR. The indi iduals wi hou colo ec al indings a e he colonoscopy we e conside ed as he con ol coho ; he emaining we e classi ied as: non-IBD, IBD, colo ec al polyps o CRC pa ien s. The mean sCD26 concen a ion dec eased, al hough non-signi ican ly, as he pa hology diagnosed Table 1: A e age sCD26 concen a ion o he g oups s udied acco ding o he colonoscopy esul . No colo ec al pa hology Clinical condi ion nMean ± SD sCD26 (ng/mL) Rec al bleeding 8 651.5 ± 190.2 Abdominal pain 10 586.1 ± 194.4 Dia hoea 9 649.5 ± 306.8 641.2 ± 241.2 Anaemia 7 370.8 ± 144.7 Cons ipa ion 4 782.7 ± 194.6 No symp oms* 30 698.5 ± 234.2 Colo ec al pa hology Diagnosis nMean ± SD sCD26 (ng/mL) Non-in lamma o y Haemo hoids 36 655.3 ± 240.4 bowel disease 612.2 ± 231.0 (non-IBD) Di e icula 28 556.7 ± 209.6 In lamma o y Coli is 20 413.2 ± 195.5 bowel disease 434.4 ± 239.7 (IBD) C ohn's disease 6 505.1 ± 355.8 Hype plas ic polyps 18 560.4 ± 201.3 Polyps Non-ad anced adenomas 40 611.1 ± 263.8 588.0 ± 246.5 Ad anced adenomas 48 566.7 ± 225.8 Duke's A 2 513.9 ± 240.4 Duke's B 12 369.8 ± 147.4 CRC 403.7 ± 278.2 Duke's C 15 402.0 ± 360.3 Duke's D 4 457.0 ± 323.0 SD: s anda d de ia ion o he mean; *: pe sonal his o y o polyps o CRC, o amilial his o y o CRC. De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 5 o 9 was mo e se e e (as seen in able 1), his is, om no col- o ec al pa hology o CRC, wi h a no iceable dec ease in he g oup wi h IBD. In ou p e ious s udy, he con ol coho was o med exclusi ely by heal hy dono s [15], whe eas in he p esen s udy i was o med by indi iduals wi h con i med no col- o ec al pa hology bu bea ing symp oms, o wi h his o y o polyps o cance . Thus we calcula ed a new cu -o o 460 ng/mL, highe han he alue o 410 ng/mL epo ed o heal hy dono s [15]. Acco ding o his cu -o , wi hin he no colo ec al pa hology g oup, indi iduals wi h anaemia showed a sub- s an ially ele a ed posi i i y a e (71.4%) as expec ed om hei mean le els. Non-IBD exhibi ed a low posi i - i y a e (28.1%), whe eas he IBD g oup eached 73.1%. This pa hology is associa ed wi h a leas a 5- old inc eased isk o CRC, ep esen ing one o he highes isk g oups based on he in lamma ion-dysplasia-ca ci- noma sequence [22]. In compliance wi h his sequence, he sCD26 posi i i y a e inc eased om no colo ec al pa hology o hype plas ic polyps and non-ad anced ade- nomas, wi h a u he inc ease in ad anced adenomas and CRC. The capabili y o colo ec al polyps o de elop in o can- ce is ela ed o he size o he lesion, he p opo ion o illous componen and he g ade o dysplasia. In ela ion o dysplasia, a mo phological ma ke o neoplas ic lesions, we obse ed a di ec (posi i e) end be ween he g ade o dysplasia and he posi i i y o he bioma ke , hough he e was no signi ican co ela ion be ween bo h pa ame e s. Conce ning ad anced adenomas, a e m commonly used o g oup adenomas ha ha e an inc eased likelihood o malignan ans o ma ion, he sCD26 posi i i y esul ed s a is ically signi ican . Recen wo ks also s udied o he po en ial ma ke s in ela ion o polyp cha ac e is ics: o he se um sul a ase ac i i y, di e ences ega ding he numbe o adenomas (single o mul iple) we e signi ican [23]; se um lep in, adiponec in and esis in also di e ed be ween con ols and pa ien s wi h adenomas o CRC, hough he e was no ela ionship wi h dysplasia, his opa hology o polyp localiza ion [24]. Table 2: Sensi i i y and speci ici y o he sCD26 a di e en cu -o alues o sepa a ing indi iduals wi h no colo ec al pa hology om hose wi h CRC. Cu -o (ng/mL) Sensi i i y (95% CI) Speci ici y (95% CI) +LR -LR 390 57.6% (38.2-74.5) 83.8% (72.9-91.6) 3.6 0.5 410 72.7% (54.5-86.7) 80.9% (69.5-89.4) 3.8 0.3 460 81.8% (64.5-93.0) 79.4% (67.9-88.3) 4.0 0.2 500 84.9% (68.1-94.8) 72.1% (59.9-82.3) 3.0 0.2 +LR: Posi i e likelihood a io; -LR: Nega i e likelihood a io. Figu e 1 Do plo ep esen ing he sCD26 concen a ion acco ding o he colonoscopic diagnosis. Ho izon al line: 460 ng/mL cu -o . 1: No col- o ec al indings (n = 68); 2: non-IBD (n = 64); 3: IBD (n = 26); 4: hype plas ic polyps (n = 18); 5: non-ad anced adenomas (n = 40); 6: ad anced adenomas (n = 48); 7: CRC (n = 33). De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 6 o 9 Table 3: Chi-squa e and Fische 's exac analyses o he clinicopa hological cha ac e is ics o polyps in ela ion o he sCD26 posi i i y Va iable Mean ± SD nsCD26+/n sCD26+ a e p sCD26 (ng/mL) Numbe 1-2 577.6 ± 244.3 28/84 33.3 0.807 3 o mo e 624.6 ± 256.1 7/24 29.2 Size ≤ 0.5 cm 525.2 ± 208.1 11/32 34.4 0.6 - 1 cm 673.9 ± 298.7 6/28 21.4 0.339 > 1 cm 579.9 ± 226.7 18/48 37.5 Loca ion ec um 549.0 ± 190.0 7/24 29.2 sigma 617.1 ± 273.7 13/44 29.5 le colon 571.7 ± 194.5 7/21 33.3 0.475 ans e se colon 427.0 ± 157.6 4/6 66.7 igh colon 662.4 ± 324.5 4/13 30.8 Mo phology sessile 592.8 ± 264.4 18/64 28.1 pedicula ed 585.3 ± 230.9 15/39 38.5 0.517 la 548.6 ± 126.5 2/5 40.0 His ology hype plas ic 560.4 ± 201.3 4/18 22.2 0.413 adenomas 597.2 ± 256.1 30/88 34.1 De ailed his ology hype plas ic 560.4 ± 201.3 4/18 22.2 ubula 605.3 ± 259.9 24/72 33.3 0.358 illous 612.6 ± 305.8 2/6 33.3 ubulo illous 529.7 ± 207.5 4/10 40.0 Dysplasia no dysplasia 560.4 ± 201.3 4/18 22.2 low-g ade dysplasia 598.7 ± 250.5 27/83 32.5 0.056 high-g ade dysplasia 562.9 ± 293.1 3/5 60.0 Adenomas non-ad anced 633.9 ± 286.9 9/40 22.5 0.048* ad anced 566.7 ± 225.8 20/48 41.7 SD: s anda d de ia ion; nsCD26+: numbe o indi iduals wi h sCD26 le els ≤ 460 ng/mL; n : o al numbe o indi iduals pe g oup; sCD26+ a e: sCD26 posi i i y a e. De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 7 o 9 In ou expe imen al se ing we ha e also e alua ed he diagnos ic pa ame e s o he sCD26. A he 460 ng/mL cu -o , he sensi i i y and speci ici y o CRC e sus non- cance g oups we e 81.8% and 72.3%, espec i ely. This speci ici y is measu ed in he amewo k o symp oma ic and asymp oma ic pa ien s bea ing in e media e benign pa hologies including non-IBD and IBD as well as polyps. When conside ing only asymp oma ic indi iduals speci- ici y inc eases o 90%, which ag ees wi h he esul s p e- iously published by ou g oup [15]; ne e heless a dec ease in sensi i i y will be expec ed in his con ex . In an asymp oma ic high- isk coho o indi iduals wi h amilial his o y o CRC o pe sonal his o y o CRC o adenoma, Hazazi e al. [25] sugges ed he use o a quan i a i e immunochemical FOBT (iFOBT) o sc een- ing o high- isk indi iduals. Excluding indi iduals wi h anaemia, ec al bleeding and IBD, hey epo ed a sensi- i i y and speci ici y o CRC o 100% and 85.3%, espec- i ely. In he classical CRC sc eening s udies in a e age- isk indi iduals, he gFOBT (guaiac-based) is ex ensi ely used, despi e i s wide ange o sensi i i y and speci ici y. The mos common es s a e he Hemoccul II® ( ehy- d a ed o un ehyd a ed) and he Hemoccul SENSA®, hough he un ehyd a ed gFOBT is he one ecom- mended o sc eening [26]. Fo he un ehyd a ed Hemoc- cul II®, he mos accu a e diagnos ic pa ame e s ha e been es ima ed wi h one- ime es ing on a Chinese [27] and an Ame ican popula ions [28]; in bo h, colonoscopy was pe o med o all indi iduals wi h posi i e o nega i e gFOBT esul s, epo ing a sensi i i y o CRC o 25 and 12.9%, and a speci ici y o 80 and 95.2%, espec i ely [27,28]. These s udies e lec a poo sensi i i y, al hough i is sligh ly imp o ed wi h epea ed annual o biennial es ing (54-80%), eaching up o 97.7% speci ici y [29,30]. On he o he hand, a 50% sensi i i y was ob ained o a one- ime ehyd a ed es ing combined wi h sigmoidos- copy, hough no speci ici y was epo ed, pe haps owing o an inc ease in he numbe o alse posi i es due o ehyd a ion [31]. When a highly sensi i e es like he Hemoccul SENSA® is used, a 71-79% sensi i i y is eached wi h sin- gle es ing, and abou 85% wi h mul iple es ing, wi h co - esponding speci ici ies o 86% and 95% [32,33]. Howe e , hese pa ame e s a e p obably o e es ima ed as hese s udies lacked colonoscopic examina ion o he nega i e cases. Besides guaic-based FOBT, iFOBT has been ecen ly o e ed as an al e na i e o a e age- isk sc eening. The s udies epo ed up o da e ha e shown ha he iFOBT is mo e adequa e o sc eening because o i s high speci ic- i y since i de ec s human globin [26]. Th oughou ou s udy, e idence was ga he ed ega d- ing he u ili y o he sCD26 in he de ec ion o ad anced Table 4: Sensi i i y and speci ici y o he sCD26 a he cu -o alue o 460 ng/mL Coho nsCD26+/n Sensi i i y (95% CI) CRC 27/33 81.8% (64.5-93.0) Ad anced adenomas 20/48 41.7% (27.6-56.8) CRC and ad anced adenomas 47/81 58.0% (46.5-68.9) Non-ad anced adenomas and ad anced adenomas 30/88 34.1% (24.3-45.0) Coho nsCD26-/n Speci ici y (95% CI) No colo ec al indings-no symp oms 27/30 90.0% (73.4-97.8) No colo ec al indings 54/68 79.4% (67.9-88.3) No colo ec al indings, non-IBD, IBD, hype plas ic polyps, non-ad anced and ad anced adenomas 191/264 72.3% (65.0-77.2) No colo ec al indings, non-IBD, IBD, hype plas ic polyps and non-ad anced adenomas 163/216 75.5% (68.5-81.0) nsCD26+: numbe o indi iduals wi h sCD26 le els ≤ 460 ng/mL; nsCD26-: numbe o indi iduals wi h sCD26 le els > 460 ng/mL; n : o al numbe o indi iduals pe g oup. De Chia a e al. BMC Cance 2010, 10:333 h p://www.biomedcen al.com/1471-2407/10/333 Page 8 o 9 adenomas. In sepa a ing CRC and ad anced adenomas om all o he g oups, he sCD26 exhibi ed a 58.0% sensi- i i y and a 75.5% speci ici y. Fo he same pa hologies (CRC and ad anced adenomas) in an asymp oma ic high- isk coho , Hazazi e al. [25] epo ed o a quan i a i e iFOBT a sensi i i y and speci ici y o 65.3% and 87.5%, espec i ely. Rega ding s udies pe o med in a e age- isk indi idu- als o he de ec ion o CRC and ad anced adenomas, gFOBT has shown a sensi i i y o 10.8-14.3% [27,28] and a speci ici y o 79.2% [27], and consequen ly is no ec- ommended o he de ec ion o ad anced lesions [4,6]. On he o he hand, iFOBT showed a sensi i i y o 33.1% and a speci ici y o 97.5%, hough hese pa ame e s we e gi en o only dis al ad anced neoplasm as compa ed o lexible sigmoidoscopy [25]. In ela ion o o he expe imen al se um bioma ke s o ad anced adenomas, he CCSA-2 has shown a 97.3% sen- si i i y wi h a 78.4% speci ici y conside ing no mal colonoscopy, hype plas ic polyps and non-ad anced ade- nomas [13], whe eas o CCSA-3 and -4 a combined sen- si i i y o 91.3% and a speci ici y o 78.7% was epo ed [14]. While sCD26 shows lowe sensi i i y, he speci ici y is equi alen e en including pa ien s wi h con ounding pa hologies such as IBD, which we e no p esen in o he s udies. Al hough sCD26 seems o pe o m adequa ely as a blood bioma ke o CRC and ad anced adenomas, inde- penden o he equen bu in e mi en bleeding unlike gFOBT o iFOBT, ou s udy p esen s some limi a ions ha should be conside ed: i) he symp oma ic popula ion included is a high- isk o CRC, wi h an ele a ed p e a- lence o colo ec al pa hology; ii) al hough no di e ences ega ding age we e de ec ed, he age ange o he pa ien s di e s om ha ecommended o sc eening; iii) he classi ica ion o he pa ien s in o he ca ego ies p oposed esul ed in se e al sub-g oups wi h a small numbe o pa ien s. The e o e, u he esea ch in a la ge popula ion and unde a sc eening con ex is desi able, along wi h he compa ison o a sensi i e gFOBT o iFOBT, and o he expe imen al non-in asi e me hods. Conclusions Ou esul s show ha measu emen o he sCD26 is a non-in asi e and easonably sensi i e assay, which could be combined wi h o he s such as he aecal occul blood es , o he ea ly diagnosis and sc eening o CRC and ad anced adenomas. Wi h his aim, we a e cu en ly ini- ia ing a mul icen ic, p ospec i e, double-blinded s udy in an a e age- isk popula ion, whe e he pe o mance o he quan i i e iFOBT and he sCD26 assay will be assessed and compa ed ega ding he gold s anda d colonoscopy. Compe ing in e es s The au ho s decla e ha hey ha e no compe ing in e es s. Au ho s' con ibu ions LD: measu emen o he sCD26 le els, da a analysis, s a is ical e alua ion, man- usc ip p epa a ion. AMRP: da a analysis, s a is ical e alua ion, manusc ip p epa a ion. FJRB: S udy design, coo dina ion o he s udy. OJC: da a analysis, manusc ip p epa a ion. DMA: Pa ien ec ui men , collec ion o samples and clinical da a. MPD: S udy design, coo dina ion o he s udy, inal e ision o he manusc ip . All au ho s ead and app o ed he inal manusc ip . Acknowledgemen s We hank he CHUVI Gas oen e ology Uni , especially D . Palla és-Pe al, D . Ma ín-G anizo and Nini. Au ho De ails 1Uni e sidad de Vigo. Facul ad de Biología. 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