title: Rarity of adenomatous polyps in ulcerative colitis and its implications for colonic carcinogenesis.
abstract: OBJECTIVE
  Despite ample research on the dysplasia to carcinoma risk in ulcerative colitis, there are scant data on the prevalence of adenomatous polyps in this population.
  
  
  METHODS
  The number and histology of all polyps detected at colonoscopies of ulcerative colitis patients aged > 50 during 2006 - 2012 were compared with similarly aged controls undergoing screening colonoscopy.
  
  
  RESULTS
  There were 206 patients with ulcerative colitis and 624 controls included in the study (mean age 61.7 ± 8.7 vs. 60.8 ± 6.1, respectively; P = 0.15). Adenomatous polyps were detected in only 13/206 colonoscopies for ulcerative colitis compared with 162 /624 controls (6.3 % vs. 25.9 %, respectively; odds ratio [OR] 0.19, 95 % confidence interval [CI] 0.1 - 0.34; P < 0.0001). When also considering all prior colonoscopies performed over 7.7 ± 4.6 years of follow-up (mean 4.1 ± 2.9 colonoscopies/patient, range 1 - 15, total 832 colonoscopies), the risk of ever finding an adenoma in ulcerative colitis patients was still significantly lower compared with controls (14.1 % vs. 25.9 %, respectively; OR 0.47, 95 %CI 0.3 - 0.72; P = 0.0005). On multivariable analysis, adenomas were positively associated with advanced age (OR 1.07/year, 95 %CI 1.03 - 1.1; P < 0.0001) and with increasing body mass index (BMI; OR 1.06/kg/m(2), 95 %CI 1.01 - 1.1; P = 0.01) and negatively associated with having ulcerative colitis (OR 0.15, 95 %CI 0.09 - 0.44; P = 0.0005). Among 115 Crohn's disease patients aged > 50 years, the rate of ever-adenomas in small-bowel Crohn's disease was similar to the controls (P = 0.8) and not influenced by 5-aminosalicylic acid use, whereas patients with colonic Crohn's disease had a significantly lower rate of adenomas compared with the controls (3.9 % vs. 25.9 %; P = 0.002).
  
  
  CONCLUSIONS
  Unlike patients with small-bowel Crohn's disease, patients with ulcerative colitis or with colonic Crohn's disease seldom develop sporadic adenomatous polyps. These data may provide novel clues to a possible role for colonic immune activation in restricting the adenoma to carcinoma sequence while propagating the dysplasia to carcinoma pathway.
authors.affiliation: Gastroenterology Department, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Shomron
authors.initials: S
authors.lastname: Ben-Horin
authors.affiliation: Gastroenterology Department, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Ziv
authors.initials: Z
authors.lastname: Izhaki
authors.affiliation: Gastroenterology Department, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Ola
authors.initials: O
authors.lastname: Haj-Natur
authors.affiliation: Institute for Medical Screening, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Shlomo
authors.initials: S
authors.lastname: Segev
authors.affiliation: Gastroenterology Department, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Rami
authors.initials: R
authors.lastname: Eliakim
authors.affiliation: Gastroenterology Department, Sheba Medical Center & Sackler School of Medicine Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Avidan
mesh_terms: D018256:Adenomatous Polyps / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D063646:Carcinogenesis; D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000150:complications*; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D003113:Colonoscopy; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors