2025 Volume 78 Issue 10 Pages 386-392
Ulcerative colitis is a well-known risk factor for colorectal cancer. Unlike in Western countries, the anorectum is the most frequent site of Crohn's disease-associated neoplasia in Japan.
In 2024, new clinical guidelines on inflammatory bowel disease (IBD)-associated gastrointestinal tumors were published. Registry studies are underway by the Japanese Society for Cancer of the Colon and Rectum and a research team supported by the Ministry of Health, Labour and Welfare.
Surveillance colonoscopy is essential, with total proctocolectomy generally recommended for ulcerative colitis-associated colorectal neoplasia. Under strict surveillance for metachronous and synchronous multiple lesions, endoscopic treatment for low-grade dysplasia may be performed, and registry studies are currently ongoing.
Early detection of anorectal tumors associated with Crohn's disease is often difficult. Abdominoperineal resection or even more extensive surgery is frequently required. Although a definitive diagnostic method has not yet been established, surveillance combining multiple imaging modalities such as colonoscopy and MRI, along with examination and biopsy under anesthesia, is being explored.
