Development of ileal adenomas after ileal pouch-anal anastomosis versus end ileostomy in patients with familial adenomatous polyposis

Background and Aims: Patients with familial adenomatous polyposis (FAP) undergo (procto)colectomy to prevent colorectal cancer from developing. Interestingly, after proctocolectomy with ileal pouch-anal anastomosis (IPAA), most patients develop adenomas in the pouch. This is not well described for patients with end ileostomy. We aimed to compare ileal adenoma development in patients with IPAA with those with end ileostomy. Methods: This historical cohort study included FAP patients with IPAA or end ileostomy who underwent surveillance endoscopies between 2001 and 2021. Primary outcomes were the proportion of patients with ileal adenomas, location of adenomas, and proportion of patients undergoing surgical excision of pouch/end ileostomy. Results: Overall, 144 patients with IPAA (n = 111) and end ileostomy (n = 33) were included. Five years after surgery, 15% of patients with IPAA had ileal adenomas versus 4% after ileostomy. At 10 years, these estimates were 48% versus 9% and at 20 years were 85% versus 43% (log-rank P <.001). Adenomas developed more often in the pouch body (95%) in the IPAA group and more often at the everted site of the ileostomy (77%) in the ileostomy group. Numbers for surgical excision of the pouch (n = 9) or ileostomy (n = 3) for polyposis or cancer were comparable. Taking into account potential confounders in a multivariable Cox regression analysis, having an IPAA was significantly associated with ileal adenoma development. Conclusions: After proctocolectomy, FAP patients with IPAA more often developed ileal adenomas than patients with end ileostomy. This could potentially affect long-term management, and patients with end ileostomy might benefit from less-frequent endoscopic surveillance.