Participation and yield of colonoscopy versus non-cathartic CT colonography in population-based screening for colorectal cancer: a randomised controlled trial

Background Screening for colorectal cancer is widely recommended, but the preferred strategy remains unidentified. We aimed to compare participation and diagnostic yield between screening with colonoscopy and with non-cathartic CT colonography. Methods Members of the general population, aged 50-75 years, and living in the regions of Amsterdam or Rotterdam, identified via the registries of the regional municipal administration, were randomly allocated (2:1) to be invited for primary screening for colorectal cancer by colonoscopy or by CT colonography. Randomisation was done per household with a minimisation algorithm based on age, sex, and socioeconomic status. Invitations were sent between June 8, 2009, and Aug 16, 2010. Participants a Findings 1276 (22%) of 5924 colonoscopy invitees participated, compared with 982 (34%) of 2920 CT colonography invitees (relative risk [RR] 1.56, 95% CI 1.46-1.68; p<0.0001). Of the participants in the colonoscopy group, 111 (9%) had advanced neoplasia of whom seven (<1%) had a carcinoma. Of CT colonography participants, 84 (9%) were offered colonoscopy, of whom 60 (6%) had advanced neoplasia of whom five (<1%) had a carcinoma; 82 (8%) were offered surveillance. The diagnostic yield for all adva Interpretation Participation in colorectal cancer screening with CT colonography was significantly better than with colonoscopy, but colonoscopy identified significantly more advanced neoplasia per 100 participants than did CT colonography. The diagnostic yield for advanced neoplasia per 100 invitees was similar for both strategies, indicating that both techniques can be used for population-based screening for colorectal cancer. Other factors such as cost-effectiveness and perceived burden shoul