Risk Factors for Pouch Neoplasia in Patients With Inflammatory Bowel Disease: A Case-Control Study

Patients with inflammatory bowel disease (IBD) undergoing total proctocolectomy with ileal pouch-anal anastomosis remain at risk of pouch neoplasia. Prior studies, based on cohorts ending in the 2010s, identified prior colorectal dysplasia and carcinoma as independent risk factors. We aimed to reassess contributors from a contemporary, prospectively maintained registry.

Patients with an ileal pouch and underlying IBD were identified from tertiary centers (2019-2026) for a case-control study. Seventeen patients with pouch neoplasia were randomly matched 1:3 to 51 patients without pouch neoplasia. Pediatric patients (<18 years) and non-IBD pouches were excluded. Univariate and multivariable analyses were performed.

Among 748 patients, 17 (2.3%) had pouch neoplasia, including 1 (5.9%) with anal intraepithelial neoplasia grade 1, 3 (17.6%) with low-grade dysplasia, 4 (23.5%) with high-grade dysplasia, and 10 (58.8%) with cancer. Five patients were diagnosed with anal squamous neoplasia, of whom 4 (80.0%) tested positive for anal human papillomavirus. On multivariable analysis, dysplasia and carcinoma in the colectomy specimen were identified as independent risk factors for pouch neoplasia (adjusted odds ratio, 6.2; 95% confidence interval, 1.1-36.7; P = .047; and adjusted odds ratio, 12.3; 95% confidence interval, 2.5-60.8; P = .002, respectively). An older age at pouch construction, a longer duration from IBD diagnosis to pouch construction, and concurrent pouchitis were significantly associated with pouch neoplasia on univariate analysis but did not remain significant on the multivariable model.

The presence of dysplasia or carcinoma in the colectomy specimen remains the strongest risk factor for pouch neoplasia. An unusual prevalence of anal squamous neoplasia was observed, with a notable presence of human papillomavirus infection.