A systematic review 1 including 1 historical chort study (186 patients), 1 cross-sectional study (41 patients) and 10 prospective cohort studies (1 413 patients) was abstracted in DARE. According to 5 population-based studies, a patient with extensive ulcerative colitis has roughly a 12% chance of developing colorectal cancer between 10 and 25 years. Combining the data from the 10 prospective cohort studies, among 1 413 patients the percentage of advanced colon cancers with bad outcomes is reduced by surveillance to 25% (European data only) or to 35% (all data). The NNT (combined data) for surveillance for 15 years (by colonoscopy every 1 - 3 years) to prevent 1 incurable cancer is 33, entailing 250 colonoscopies.
Primary/Secondary Keywords