Incidence, Risk Factors and Outcomes of Cancer of the Anal Transitional Zone in Patients with Ulcerative Colitis

Background and Aims Performing a mucosectomy with a hand-sewn ileal pouch-anal anastomosis [IPAA] for ulcerative colitis [UC] theoretically reduces the risk of carcinoma arising from the anal transitional zone [ATZ]. Although current guidelines suggest a stapled anastomosis due to the low incidence of cancer after pouch surgery in UC patients, only a few small series have addressed the oncological advantage of mucosectomy. Therefore, we aimed to investigate the incidence of ATZ/pouch cancer. Methods A total of 1970 UC patients who underwent surgery between April 1987 and December 2018 were included. We retrospectively analysed the incidences of primary ATZ cancer in the original operative specimen and de novo ATZ/pouch cancer after surgery. Possible risk factors for primary ATZ cancer and the pouch survival rate were assessed. Results Fourteen [6.4%] primary ATZ cancers developed in 220 UC-colorectal cancer [CRC] cases. Multiple (odds ratio [OR] = 8.79, 95% confidence interval [CI] 2.77–27.83, p < 0.01) and rectal [OR = 6.48, 95% CI 1.41–29.7, p = 0.01] cancers were identified as independent risk factors for primary ATZ cancer. Four of 1970 [0.2%] patients developed de novo ATZ/pouch cancer and dysplasia. The 10-year estimated cumulative pouch survival rate was not significantly different between stapled IPAA and hand-sewn IPAA cases [95.9% and 97.3%, p = 0.25]. Conclusion The risk of de novo ATZ/pouch cancer and dysplasia was rare. The decision to perform a hand-sewn or a stapled IAA should be made on a case-by-case basis. However, the relatively high incidence of primary ATZ cancer in UC patients with CRC suggests that mucosectomy should be recommended for this patient group.