High rate of advanced adenoma detection in 4 rounds of colorectal cancer screening with the fecal immunochemical test.
Few data have been published on the performance of colorectal cancer (CRC) screens that use multiple rounds of the fecal immunochemical test (FIT). We evaluated outcomes of 4 screening rounds in over 7 years in an Italian population-based program. We conducted a prospective cohort study of 2959 average-risk subjects, aged 50-74 years, who were invited for the first screening round in 2001. We assessed the participation rate, the yield of advanced adenomas and CRC detected in the screening examinations, and we collected information about interval CRCs, with a follow-up period of 8.5 years. Participation in each round varied from 56% to 63%; 48.1% of eligible subjects attended all 4 invitations. The positive predictive value of the FIT for advanced neoplasia (CRC or advanced adenoma) was 40% at the first round, and approximately 33% in the subsequent rounds. This decrease was attributable mainly to a decrease in the detection of CRC, although a high rate of advanced adenomas (range, 0.8%-1.7%) was observed over all rounds. To find one advanced neoplasia in the study period the number of people that needed to be screened was 28, and the number of tests needed was 74. About 60% of invited individuals participated in every single round of FIT screening for CRC, but less than 50% attended all 4 tests. A high detection rate of advanced adenomas in all rounds indicates that FIT screening could have a higher impact on incidence of CRC than the guaiac fecal occult blood test.