Risk of cancer and secondary proctectomy after colectomy and ileorectal anastomosis in familial adenomatous polyposis

Purpose The aim of our retrospective study was to review the outcome of patients undergoing colectomy with ileorectal anastomosis (IRA) due to familial adenomatous polyposis (FAP) in Finland during the last 50 years. Methods The cumulative risk of rectal cancer and the rate of anus preservation were analyzed. A total of 140 FAP patients with previous colectomy combined with ileorectal anastomosis were included. Kaplan-Meier analysis was performed to evaluate cumulative risks. Results Secondary proctectomy was performed for 39 (28 %) of 140 patients. The cumulative risk of secondary proctectomy was 53 % at 30 years after colectomy with IRA. A total of 17 (44%) secondary proctectomies were performed due to cancer or suspicion of cancer, and another 17 (44 %) secondary proctectomies were performed due to uncontrollable rectal polyposis. During our study, the anus preservation rate in secondary proctectomies was 49 %. The cumulative risk of rectal cancer was 24 % at 30 years after colectomy with IRA. Therefore, the cumulative rectal cancer mortality 30 years after colectomy with IRA was 9 %. Conclusions Proctocolectomy and ileal pouch-anal anastomosis (IPAA) should be favored as a primary operation for patients not having technical or medical contraindications for it because colectomy with IRA carried a rectal cancer risk of 13 % with a mortality of 7 % during our study, and because IPAA is likely to succeed better at earlier phase of the disease. Patients with attenuated FAP had no rectal cancer in our study, and they may form a group where IRA should still be the first choice as an exception.