Ulcerative colitis and colon carcinoma: epidemiology, surveillance, diagnosis, and treatment

1. Is there a risk of developing colon cancer in patients with chronic ulcerative colitis? There is a clear relationship between chronic ulcerative colifts and the risk of developing colorectal carcinoma. The overall incidence of ulcerative colitis may be as much as l0-fold higher than what other epidemiologic studies in the Westem World have reported previously. The survival decrease in patients with ulcerative colitis is clearly related to colon cancer and not to other medical conditions. The two best established risk factors for developing colorectal cancer in chronic ulcerative colitis are duration of disease and anatomic extent of disease. Colorectal cancer is only rarely encountered when the total duration of colitis is less than 8 to 10 years, but thereafter the risk of cancer rises at the rate of approximately 0.5% to 2% per year. Patients with extensive colitis, that is, those with disease proximal to the splenic flexure, are at the greatest risk of developing cancer, whereas those with only proctitis have very little risk for colorectal cancer. Persons with left-sided colitis are also at risk, although this appears to be lower than in those with pancolitis. The age of onset as a risk factor remains controversial. Although some studies report that onset of colitis at a young age is a risk factor for subsequent colorectal cancer, the bulk of evidence suggests that childhood onset of colitis does not confer an added risk independent of total disease duration and anatomic extent. Nevertheless, there were disturbing data presented by the panel suggesting that in patients diagnosed with colitis before the age of 15 years and who are then followed up to the age of 50 years, there is up to a 50% risk of developing colorectal carcinoma. In addition, several studies have indicated that the small subset of patients with primary sclerosing cholangitis may be at high risk for developing colorectal carcinoma. A family history of colon cancer is associated with a twoto threefold greater risk for colon cancer in persons with ulcerative colitis as opposed to those with colorectal carcinoma unrelated to colitis. It is likely that other genetic subgroups will be identified that are also at increased risk.