RESUMO
BACKGROUND AND STUDY AIMS: 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 >â50 during 2006â-â2012 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 61.7â±â8.7 vs. 60.8â±â6.1, respectively; Pâ=â0.15). Adenomatous polyps were detected in only 13/206 colonoscopies for ulcerative colitis compared with 162â/624 controls (6.3â% vs. 25.9â%, respectively; odds ratio [OR] 0.19, 95â% confidence interval [CI] 0.1â-â0.34; Pâ<â0.0001). When also considering all prior colonoscopies performed over 7.7â±â4.6 years of follow-up (mean 4.1â±â2.9 colonoscopies/patient, range 1â-â15, total 832 colonoscopies), the risk of ever finding an adenoma in ulcerative colitis patients was still significantly lower compared with controls (14.1â% vs. 25.9â%, respectively; OR 0.47, 95â%CI 0.3â-â0.72; Pâ=â0.0005). On multivariable analysis, adenomas were positively associated with advanced age (OR 1.07/year, 95â%CI 1.03â-â1.1; Pâ<â0.0001) and with increasing body mass index (BMI; OR 1.06/kg/m(2), 95â%CI 1.01â-â1.1; Pâ=â0.01) and negatively associated with having ulcerative colitis (OR 0.15, 95â%CI 0.09â-â0.44; Pâ=â0.0005). Among 115 Crohn's disease patients agedâ>â50 years, the rate of ever-adenomas in small-bowel Crohn's disease was similar to the controls (Pâ=â0.8) 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 (3.9â% vs. 25.9â%; Pâ=â0.002). CONCLUSION: 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.