Risk factors for secondary proctectomy in patients with familial adenomatous polyposis

Colectomy and ileorectal anastomosis (IRA) or restorative proctocolectomy are performed for prophylaxis in familial adenomatous polyposis (FAP). After IRA patients may require secondary proctectomy for worsening polyposis or rectal cancer. Outcomes after IRA were evaluated and risk factors predictive of progressive rectal disease identified.

Parametric survival analysis was used to identify predictors of progressive rectal disease in all patients undergoing an IRA for FAP at a single centre. Hazard ratios (HRs) were calculated for phenotype, genotype, sex, age at surgery and presence of colonic cancer.

Of 427 patients who underwent IRA, 48 (11.2 per cent) developed rectal cancer and 77 (18.0 per cent) required proctectomy for worsening polyposis over a median follow-up of 15 (range 7-25) years. By the age of 60 years half of the patients retained their rectum. Rectal polyp count exceeding 20 (HR 30.99, 95 per cent confidence interval 9.57 to 100.32; P < 0.001), APC mutation codon 1250-1450 (HR 3.91, 1.45 to 10.51; P = 0.007), colonic polyp count 500 or more (HR 2.18, 1.24 to 3.82; P = 0.006) and age less than 25 years at the time of surgery (HR 1.99, 1.17 to 3.37; P = 0.011) were independent predictors of progressive rectal disease.

The risk of proctectomy after IRA for FAP is based on patient genotype, phenotype and age at surgery.