Risk of Developing Adenomas and Carcinomas in the Ileal Pouch in Patients With Familial Adenomatous Polyposis

Background & Aims: At present, more than half of patients with familial adenomatous polyposis (FAP) are treated with a proctocolectomy and an ileal pouch-anal anastomosis (IPAA). Originally it was thought that this procedure would eliminate the risk of developing rectal cancer. However, an increasing number of studies reported development of adenoma and carcinoma in the pouch. The aim of this study was to evaluate the long-term risk of developing adenomas and carcinomas in the pouch in a large cohort of Dutch FAP patients. Methods: A total of 254 patients with FAP who underwent an IPAA were selected from the Dutch Polyposis Registry. The results of the surveillance examinations and the pathology reports were analyzed. Surveillance with chromoendoscopy was offered to a subgroup of patients. Results: Full information on follow-up was available in 212 (84%) patients. These patients (56% male) underwent a total of 761 endoscopies. The mean follow-up was 7.9 years (range, 0.4-20.3 years). The cumulative risk of developing an adenoma in the pouch at 10-year follow-up was 45%. Twenty-five patients (11.8%) developed an adenoma with advanced pathology, and 4 (1.9%) developed a carcinoma. The cumulative risk of developing a pouch carcinoma at 10-year follow-up was 1%. A very high prevalence (75.7%) of adenomas was found in a subgroup of patients who were examined with chromoendoscopy. Conclusions: This study demonstrated that although the risk of developing adenomas in the pouch after an IPAA is high, the risk of malignant degeneration appears to be low. The use of chromoendoscopy improves the detection of small adenomas.