Rectal cancer risk in older patients with familial adenomatous polyposis and an ileorectal anastomosis: a cause for concern.

The risk of rectal cancer in 224 patients with familial adenomatous polyposis with an ileorectal anastomosis has been estimated by life-table analysis. Until the age of 50 years the cumulative risk is reasonably low at 10 per cent (95 per cent confidence interval 4.5-16 per cent), increasing sharply to 29 per cent (95 per cent confidence interval 18-40 per cent) by the age of 60 years. This means that surveillance of the retained rectum in older patients must either be improved or they should undergo restorative proctocolectomy in earlier middle age.