Ileorectal anastomosis is appropriate for a subset of patients with familial adenomatous polyposis

Background & Aims: This study reevaluates the risk of rectal cancer and the frequency of subsequent proctectomy for nonmalignant causes in patients wi th familial adenomatous polyposis (FAP) who have undergone colectomy with i leorectal anastomosis (IRA). Potential risk factors for rectal cancer in th is setting are also examined, and recommendations for the choice of surgica l procedure are made. Methods: The national polyposis registries in Denmark , Finland, The Netherlands, and Sweden included 659 patients undergoing sur gery with IRA in 1940-1997. Kaplan-Meier analysis and Cox regression analys is were performed to evaluate cumulative risk, survival, and predictive ris k factors. Results: Rectal carcinoma was diagnosed in 47 patients, with a c umulative 40-year risk of 0.32. The cumulative risk according to chronologi c age was 0.30 at age 60, and higher in patients undergoing surgery above a ge 25 (P 0.0016). Chronologic age was the only independent risk factor (P = 0.0016). The cumulative 5-year survival rate after rectal carcinoma was 0. 60. The ape mutation was known in 167 patients, of whom I had rectal cancer . The cumulative 40-year risk of secondary proctectomy was 0.70, and higher in patients with a mutation in codon 1250 -1500 than outside this region ( P = 0.005). However, all 7 rectal cancers were found in the latter group. N one of the 18 patients with attenuated FAP (mutation in codon 0-200 or >150 0) had a secondary proctectomy. Conclusions: IRA is recommended in (1) youn g patients with few rectal adenomas and a family history of a mild phenotyp e and (2) patients with attenuated FAP (a mutation in codon 0-200 or >1500) , provided there is acceptance of life-long rectal surveillance. Patients w ith many rectal polyps and/or a family history of severe polyposis should b e offered a restorative proctocolectomy with an ileal pouch-anal anastomosi s.