Characteristics, Clinical Outcomes, and Prognosis of Anal and Pouch-related Carcinoma in Patients with Crohn's Disease

BACKGROUND:This study described the clinical characteristics, outcomes, and prognosis of Crohn's disease (CD) patients with anal cancer in a tertiary referral center.METHODS:The electronic medical records of 35 adult CD patients, including CD of the pouch, with anal carcinoma evaluated at Mayo Clinic Rochester, Florida, or Arizona between January 1989 and August 2022 were retrospectively reviewed.RESULTS:Before cancer diagnosis, patients with pouch-related carcinoma had a shorter median duration of inflammatory bowel disease than those with anal carcinoma (10 vs 26 years). Twenty-six patients (74%) had perianal diseases or rectovaginal fistula, and 35% had a history of human papillomavirus infection. Twenty-one patients (60%) were diagnosed with cancer by anal examination under anesthesia (EUA). More than half of adenocarcinomas were mucinous. Sixteen patients (47%) were American Joint Committee on Cancer (AJCC) Tumor Nodes Metastasis (TNM) stage 3, and 83% were treated by surgery. At last follow-up, 57% of patients were alive without cancer. The 1-, 3- and 5-year overall survival rates were 93.8% (95% confidence interval [CI], 85.7%-100%), 71.5% (95% CI, 56.4%-90.7%), and 67.7% (95% CI, 51.2%-87.7%), respectively. Advanced AJCC TNM stage (hazard ratio, 3.20 per stage; 95% CI, 1.05-9.72; P = .040) was significantly associated with increased risk of death, whereas the period of cancer diagnosis in 2011-2022 (HR, relative to 1989-2000, 0.16; 95% CI, 0.04-0.72; P = .017) was significantly related to decreased risk of death.CONCLUSIONS:Anal and pouch-related carcinomas were rare complications of CD, and long-standing perianal diseases were an important risk factor. Anal EUA improved the diagnostic yield. Newer cancer treatment strategies and surgery were associated with excellent survival outcome.