Long-term Risk of Cancer Following Ileal Pouch-anal Anastomosis for Ulcerative Colitis

Background The overall risk of cancer following ileal pouch-anal anastomosis [IPAA] is unknown, and pouch cancer surveillance is controversial. We evaluated long-term risk of cancer in a national cohort of patients with ulcerative colitis and IPAA, with emphasis on pouch cancer. Methods Data on incident cancers were extracted from the national Danish Cancer Registry. Incidence rates for all site-specific cancers were compared between patients with IPAA and a gender- and age-matched comparison cohort from the background population to obtain incidence rate ratios [IRRs]. Results A total of 1723 patients with IPAA, operated for ulcerative colitis in the period 1980-2010, were matched to 8615 individuals from the background population. During a median follow-up of 12.9 years (interquartile range [IQR] 7.7-19.6 years), two pouch cancers [0.12%] were found after 16 and 27 years, respectively. In the population comparison cohort, 38 intestinal cancers [0.45%] were found, of which 35 were colorectal. The risk of hepatobiliary cancer was higher for patients with IPAA {IRR = 13.0 (95% confidence interval [CI]: 3.1-76.1)}, and half of the affected patients had coexisting primary sclerosing cholangitis. The risk of cancer overall following IPAA was identical to that of the comparison cohort: IRR = 1.05 [0.84-1.31]. Conclusions Pouch cancer following IPAA is very rare, questioning the need for general, rather than selective, surveillance. The overall cancer risk is comparable to that of the background population, and the increased risk of hepatobiliary cancer is likely an effect of coexisting liver disease and not causally related to IPAA.