Clinical Question

Does an invitation to receive a colonoscopy reduce the incidence and mortality of colorectal cancer (CRC) compared with usual care?

Bottom Line

In the first randomized trial of CRC screening using colonoscopy, a smaller than expected reduction in CRC incidence was seen in the intention-to-treat (absolute risk reduction [ARR] = −0.22% over 10 years; number needed to invite = 455) and adjusted per-protocol analyses (ARR = −0.38%; P < .05; number needed to screen = 263). The same was true for reduction in CRC mortality in the intention-to-treat (ARR = −0.03%; P = not significant) and per-protocol analyses (ARR = −0.15%; P < .05). The lower than expected mortality reduction may be explained in part by improvements in treatment and the modest duration of follow-up. The authors were careful to adjust for differences between invitees who accepted colonoscopy and those who did not (to avoid the healthy volunteer bias), although unmeasured confounding is still possible. Trials comparing fecal immunochemical tests with colonoscopy are nearing their conclusion, and the results may add further clarity. (Level of Evidence = 1b)