Pouch cancer in familial adenomatous polyposis. Incidence, risk factors and literature review: a propos of three rare cases.

[BACKGROUND] Development of pouch cancer is a great challenge to both surgeons and patients with familial adenomatous polyposis (FAP) after restorative proctocolectomy (RPC).

[AIMS] We aimed to present our experience with pouch cancer diagnosis and review literature data regarding incidence and associated risk factors.

[METHODS] This retrospective study enrolled FAP patients undergoing RPC between 1981 and 2023 in our academic institution. It included only J-pouch stapled patients with at least three years of follow-up. Patients' demographics and disease features were retrieved.

[RESULTS] After excluding seven patients, we selected 87 RPC, and three cases (3.4%) of pouch cancer were identified. They were diagnosed in three men aged 23-40 years at RPC and 41-62 years at cancer diagnosis. Interval from RPC to pouch cancer diagnosis varied from 11.6 to 20 years (average 14.6 years). All patients had colorectal cancers (CRC) detected in the specimen from the index surgery, two of them with multicenter lesions. A brief review of the literature series showed that pouch cancer has been detected in incidences ranging from 0.8 to 3.4%. Male sex, CRC in the RPC specimen, pouch phenotype during follow-up and an association with duodenal adenomas are considered risk factors.

[CONCLUSIONS] Pouch cancer is a rare event associated with specific risk factors. After RPC, all patients should undergo endoscopic surveillance, with special attention to those who develop an aggressive phenotype during the first decade of follow-up.

[CENTRAL MESSAGE] Familial adenomatous polyposis (FAP) is an autosomal dominant disease associated with mutations in the APC gene. As a dominantly inherited cancer-predisposing syndrome, the main challenge of FAP management is the significant risk of CRC that requires prophylactic colectomy in a timely manner aiming to reduce colorectal cancer (CRC) risk while maintaining quality of life. Cancer prevention is most usually accomplished through restorative procedures such as total colectomy with ileorectal anastomosis (IRA) or a restorative proctocolectomy with ileoanal anastomosis (RPC). The development of ileoanal pouch cancer is not so common in patients with FAP, even in specialized centers.

[PERSPECTIVES] Pouch cancer is a rare disease diagnosed in incidences varying from 0.8 to 3.4% in worldwide FAP series. Male patients, presence of CRC in the RPC specimen, colorectal phenotype, and association with duodenal adenomas are considered the main risk factors. Pouch adenomas develop after both hand-sewn or stapled anastomosis. Pouch polypectomy might prevent the development of adenocarcinomas, as patients under surveillance are diagnosed with more localized diseases.