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Adenomatous polyps in ulcerative colitis and colonic Crohn's disease: less frequent, but does this change surveillance strategy?

The association between inflammatory bowel disease (IBD) and colorectal cancer (CRC) has been known for several decades, with CRC remaining one of the most feared complications. Early studies reported an excess risk of CRC in ulcerative colitis patients; however, in these reports, which were published from tertiary referral centers, patients with severe disease were over-represented. In themeta-analysis by Eaden et al. from 2001 [1], the cumulative probability of CRC in ulcerative colitis was 2% by 10 years, 8% by 20 years, and 18% by 30 years. Chronic inflammation is thought to be one of the key factors in the pathogenesis, together with genetic predisposition [2]. More recently, a lower risk of CRC was reported in a meta-analysis of population-based studies, with an average of 1.6% of ulcerative colitis patients diagnosed with CRC during the first 14 years of follow-up.The pooled standardized incidence ratio (SIR) was 2.4 (95% confidence interval [CI] 2.1– 2.7) [3]. However, the interpretation of SIRs has to be adjusted for sporadic CRC rates in the background population and these may show large geographic variation. In contrast, until recently few data were available on the prevalence of sporadic adenomas in patients with ulcerative colitis or Crohn’s disease. Adenomas are mainly sharply delineated, with or without a stalk, and often show a smooth surface; the differentiation from IBD/colitis-associated neoplasms, especially in affected areas, is sometimes troublesome. The distinction between lesions is also important because of possible differences in the molecular pathogenesis and risk factors [4]. In the current issue of Endoscopy, Ben-Horin et al.[5] report on the prevalence of adenomatous polyps in patients with ulcerative colitis aged 50 years or older compared with a matched control population at the Gastroenterology Department of Sheba Medical Center. The major findings of this retrospective study were that the rate and number of adenomatous polyps in non-affected areas were significantly lower in ulcerative colitis patients (6.3% vs. 25.9%; odds ratio [OR]any adenoma=0.15, 95%CI 0.09–0.44) compared with controls during index colonoscopies performed between 2006 and 2012.The difference between ulcerative colitis patients and controls remained significant when ever-adenoma rates were analyzed (14.1% vs. 25.9%; OR= 0.47, 95%CI 0.3–0.72). A clear strength of the paper is the very detailed data collection and statistical analysis. The authors were able to perform multiple adjustments and sensitivity analyses to control for possible confounders. As an example, screening colonoscopies for all controls were performed during 2011–2012, but an adjustment for the potential differences in colonoscopy techniques confirmed the lower adenoma rate in ulcerative colitis (OR= 0.24, 95%CI 0.1–0.53; P=0.0005). The authors also studied the possible risk factors, including sex, age, body mass index (BMI), smoking, alcohol consumption, family history of CRC, and aspirin or statin use. While ulcerative colitisassociated CRCwas reported to be associatedwith young age at diagnosis [6], disease extent [7], disease duration [6], primary sclerosing cholangitis (PSC) [8], and family history of IBD [9] in previous studies, ulcerative colitis diagnosis, male sex, age, and BMI were identified as being associated with adenoma risk in the present cohort. In addition, patients with colonic, but not ileal, Crohn’s disease also had a significantly lower rate of adenomas compared with controls (3.9% vs. 25.9%; P= 0.002). In contrast, the overall rate of any polyp did not differ between the two groups, mostly because of the high frequency of inflammatory polyps (18%) in ulcerative colitis patients. The finding from the study by Ben-Horin et al. [5] of a low prevalence of adenomatous polyps in ulcerative colitis patients is in linewith some earlier reports [10,11]. However, these studies had im-