Ulcerative colitis. Colorectal cancer risk in an unselected population.

One hundred twenty-seven patients were studied, representing the unselected population of patients with ulcerative colitis from a defined catchment area of about 70,000 inhabitants during 1961-1983. Seventy-seven patients had total colitis, and 50 patients had left-sided colitis. No prophylactic colectomy was performed. Despite this and a comprehensive follow-up of patients with long-standing, extensive colitis, primary colorectal carcinomas were diagnosed in only three patients, all of whom had total colitis. This was significantly (p less than 0.001) more than the expected number of patients with colorectal cancer in this subgroup, namely, 0.13. There were no deaths in colorectal carcinoma. Factors determining completeness of inclusion are discussed, and it is concluded that, in an unselected series of patients with ulcerative colitis, close cancer surveillance is indicated, although prophylactic surgery does not seem to be generally warranted.