Suitability of surveillance colonoscopy for patients with ulcerative colitis to detect colorectal cancer: current guidelines miss some early-stage cases.

Surveillance colonoscopy (SC) is considered important for the early detection and treatment of colorectal cancer (CRC) in patients with ulcerative colitis (UC). Here, we investigated whether current guidelines are appropriate in preventing UC patients from being diagnosed with CRC at an incurable stage. Among 1583 patients under treatment for UC, 27 patients were diagnosed with CRC. Of these, we excluded two patients who had not undergone colonoscopy before CRC diagnosis. We then divided the remaining patients into three groups based on colonoscopy interval (A, 1 year or less; B, between 1 and 2 years; and C, 2 years or longer). Fifteen patients had tubular adenocarcinomas, and 10 had other types (8 poorly differentiated adenocarcinomas, 1 mucinous adenocarcinoma, 1 endocrine cell carcinoma). Five (20%) of 25 patients developed CRC within 8 years after the onset of UC, of which one case was detected at stage IV. Six patients were classified into group A, 8 into group B, and 11 into group C. On distribution by histologic type, tubular adenocarcinomas were detected in stages 0 - II in 100% in group A, 100% in group B, and 57.1% in group C. In contrast, other types of carcinomas were detected in stage 0 - II in 100% in group A, 40% in group B, and 0% in group C. Current guideline recommendations for SC are not sufficient for the detection of early stage CRC in patients with UC. SC should be commenced earlier than recommended in the current guidelines and repeated annually.