Prior colorectal neoplasia is associated with increased risk of ileoanal pouch neoplasia in patients with inflammatory bowel disease.

Background & Aims: Although restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) substantially reduces the risk of colorectal cancer in patients with inflammatory bowel disease (IBD), subsequent pouch neoplasia can develop. There are few data on the incidence of and risk factors for neoplasia, so there is no consensus on the need for pouch surveillance. We aimed to determine the cumulative incidence of pouch neoplasia in patients with IBD and identify risk factors for developing pouch neoplasia.

Methods: We searched the Dutch Pathology Registry (PALGA) to identify all patients with IBD and IPAA in The Netherlands from January 1991 to May 2012. We calculated the cumulative incidence of pouch neoplasia and performed a case-control study to identify risk factors. Demographic and clinical variables were analyzed with univariable and multivariable Cox regression analyses.

Results: We identified 1200 patients with IBD and IPAA; 25 (1.83%) developed pouch neoplasia, including 16 adenocarcinomas. Respective cumulative incidences at 5, 10, 15, and 20 years were 1.0%, 2.0%, 3.7%, and 6.9% for pouch neoplasia and 0.6%, 1.4%, 2.1%, and 3.3% for pouch carcinoma. A history of colorectal neoplasia was the only risk factor associated with pouch neoplasia. Hazard ratios were 3.76 (95% confidence interval, 1.39-10.19) for prior dysplasia and 24.69 (95% confidence interval, 9.61-63.42) for prior carcinoma.

Conclusions: The incidence of pouch neoplasia in patients with IBD without a history of colorectal neoplasia is relatively low. Prior dysplasia or colon cancer is associated with an approximate 4- and 25-fold increase in risk, respectively, of developing pouch neoplasia.