Ileoanal pouch cancers in ulcerative colitis and familial adenomatous polyposis: A systematic review and meta-analysis

Introduction: Restorative proctocolectomy results in the formation of a pouch that adapts to a more colonic phenotype. The incidence of cancer of the pouch is thought to be low with most societal guidelines differing on their recommendations for surveillance. Aims: We conducted a systematic review with meta-analysis to report the incidence of cancer in all pouch patients. Methods: The Embase, Embase classic and PubMed databases were searched between June 1979– June 2021. A random effects model was performed to find the pooled incidence of pouch cancer. In addition, we also looked for risk factors for pouch cancers. Results: Forty-six studies were included. In 19,964 patients with Ulcerative Colitis (UC) the pooled incidence of pouch cancer was 0.0030 (95% CI: 0.0016 -0.0055). In 3741 patients with Familial Adenomatous Polyposis (FAP) the pooled incidence of pouch cancer was 0.01 (95% CI: 0.01 – 0.02). In UC most pouch cancers were found to occur in the pouch body (0.59 (95% CI: 0.29–0.84)). Conclusions: The findings suggest that the pooled incidence of pouch cancer in UC is similar to that which was previously published, and this is the first meta-analysis to report a pooled incidence for pouch cancer in FAP.