Long-term outcomes of pouch surveillance and risk of neoplasia in familial adenomatous polyposis.

Background: Long-term pouch surveillance outcomes for familial adenomatous polyposis (FAP) are unknown. We aimed to quantify surveillance outcomes and to determine which of selected possible predictive factors are associated with pouch dysplasia.

Methods: Retrospective analysis of collected data on 249 patients was performed, analyzing potential risk factors for the development of adenomas or advanced lesions ( ≥ 10 mm/high grade dysplasia (HGD)/cancer) in the pouch body and cuff using Cox proportional hazards models. Kaplan-Meier analyses included landmark time-point analyses at 10 years after surgery to predict the future risk of advanced lesions.

Results: Of 249 patients, 76 % developed at least one pouch body adenoma, with 16 % developing an advanced pouch body lesion; 18 % developed an advanced cuff lesion. Kaplan-Meier analysis showed a 10-year lag before most advanced lesions developed; cumulative incidence of 2.8 % and 6.4 % at 10 years in the pouch body and cuff, respectively. Landmark analysis suggested the presence of adenomas prior to the 10-year point was associated with subsequent development of advanced lesions in the pouch body (hazard ratio [HR] 4.8, 95 %CI 1.6-14.1;  = 0.004) and cuff (HR 6.8, 95 %CI 2.5-18.3;  < 0.001). There were two HGD and four cancer cases in the cuff and one pouch body cancer; all cases of cancer/HGD that had prior surveillance were preceded by ≥ 10-mm adenomas.

Conclusions: Pouch adenoma progression is slow and most advanced lesions occur after 10 years. HGD and cancer were rare events. Pouch phenotype in the first decade is associated with the future risk of developing advanced lesions and may guide personalized surveillance beyond 10 years.