Factors affecting the risk of rectal cancer following rectum-preserving surgery in patients with familial adenomatous polyposis.

PURPOSE: Rectum-preserving surgery is one of the most common surgeries for familial adenomatous polyposis (FAP). It is appropriate to analyze factors influencing risk of rectal cancer after rectum-preserving surgery in FAP patients.
METHODS: Three hundred twenty-two patients with FAP (169 males, 153 females) who had undergone rectum-preserving surgery and were part of 1050 FAP patients registered at our FAP registry were included in the study. Postoperative survival was investigated and cause of death was elucidated from the death certificate or by inquiry to the hospitals that registered the patients. For risk analysis, log-rank tests were used.
RESULTS: Forty-four cases developed invasive cancer within a mean interval of 119 months after surgery. Cumulative risk of rectal cancer was 24.2 +/- 7 percent (mean +/- limit of 95 percent confidence interval) at 15 years. Influencing risk factors for rectal cancer were a postoperative period over ten years or age over 44 years, a rectum longer than 7 cm, and dense polyposis. Other factors such as sex and cancer in the colon at initial surgery were not correlated with risk.
CONCLUSION: The rectum may be reasonably preserved in patients with FAP when polyps in the rectum are sparse, ileorectal anastomosis is made on or below the peritoneal reflection, and patients continue having rectal examinations for life.