Invitation to a single colonoscopy has only modest impact on colorectal cancer incidence (NordICC)

Clinical Question

Does an invitation to colonoscopy reduce the incidence of colorectal cancer and colorectal cancer mortality 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 both the intention-to-treat (absolute risk reduction [ARR] = -0.22% over 10 years; NNI = 455) and adjusted per-protocol analyses (ARR = -0.38%; P < .05; NNS = 263). The same was true for reduction in CRC mortality in the intention-to-treat analysis (ARR = -0.03%; P = NS) and per-protocol analysis (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 try 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 test with colonoscopy are nearing their conclusion, and the results may add further clarity. 1b

Study design: Randomized controlled trial (single-blinded)

Funding: Government

Setting: Population-based


Mark H. Ebell, MD, MS
University of Georgia
Athens, GA

Discuss this POEM



Colonoscopy as a screening tool

Not cost effective as a mass screening tool

Roland Michael Grad

Screening colonoscopy?

How will policy makers be able to justify paying for this in the context of a publicly funded health care system?

Howard David Koseff



Bertus Johannes Reitsma

indication for colonoscopy

there is a very large over treatment with endoscopy in genera !


Single colonoscopy

In practical teems, not helpful


crc screening

undecided as yet


invitation for colonoscopy

may only minimally reduce dx of CRC



Very good