Risk factors for rectal cancer morbidity and mortality in patients with familial adenomatous polyposis after colectomy and ileorectal anastomosis.

PURPOSE: The aims of the study were to investigate the effects of ileorectal anastomosis and the follow-up program on rectal cancer morbidity and mortality and to identify risk factors that predict the fate of the rectal stump. METHODS: One hundred ninety-five patients with familial adenomatous polyposis on whom an ileorectal anastomosis was performed between 1957 and the end of 1995 were included. Median follow-up time was 14 (range, 1-39) years. The cumulative risks of rectal cancer and rectal excision were estimated using survival analysis. RESULTS: Eighteen patients (9.2 percent) developed cancer, 17 in the retained colorectal segment and one on the ileal side of the anastomosis, and nine died of their cancer during the study period. The cumulative rectal cancer morbidity and mortality 20 years after ileorectal anastomosis was 12.1 percent (95 percent confidence interval = 5.7-18.5) and 7 percent (95 percent confidence interval = 2-12), respectively. The cumulative age-dependent risk of rectal cancer was 22.9 percent (95 percent confidence interval = 11.4-34.5) and 25.7 percent (95 percent confidence interval = 13.2-38.2) at the ages of 60 and 70 years, respectively. The corresponding cumulative mortality was 11.1 percent (95 percent confidence interval = 2.9-19.3) at the age of 70 years. Patients with dense polyposis at colectomy had an increased risk for cancer in the retained colorectal segment compared with patients with intermediate or sparse polyposis (P = 0.04). Sixty-six patients (34 percent) had their rectum removed, and the cumulative rectal excision rate 35 years after ileorectal anastomosis was 65.5 percent (95 percent confidence interval = 53-78). CONCLUSION: Patients on whom ileorectal anastomosis was performed had, despite the high rectal excision rate, a substantial risk of developing cancer in the retained colorectal segment, with an ensuing high mortality. Our results indicate that patients with dense polyposis should undergo restorative proctocolectomy as primary operation for familial adenomatous polyposis. In younger patients with intermediate or sparse polyposis and good expected follow-up compliance, ileorectal anastomosis still is an alternative.