Clinician Article

Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death.

  • Bretthauer M
  • Loberg M
  • Wieszczy P
  • Kalager M
  • Emilsson L
  • Garborg K, et al.
N Engl J Med. 2022 Oct 27;387(17):1547-1556. doi: 10.1056/NEJMoa2208375. Epub 2022 Oct 9. (Original)
PMID: 36214590
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  • Public Health
    Relevance - 7/7
    Newsworthiness - 6/7
  • Gastroenterology
    Relevance - 7/7
    Newsworthiness - 5/7
  • Family Medicine (FM)/General Practice (GP)
    Relevance - 6/7
    Newsworthiness - 5/7
  • General Internal Medicine-Primary Care(US)
    Relevance - 6/7
    Newsworthiness - 5/7
  • Oncology - Gastrointestinal
    Relevance - 6/7
    Newsworthiness - 5/7


BACKGROUND: Although colonoscopy is widely used as a screening test to detect colorectal cancer, its effect on the risks of colorectal cancer and related death is unclear.

METHODS: We performed a pragmatic, randomized trial involving presumptively healthy men and women 55 to 64 years of age drawn from population registries in Poland, Norway, Sweden, and the Netherlands between 2009 and 2014. The participants were randomly assigned in a 1:2 ratio either to receive an invitation to undergo a single screening colonoscopy (the invited group) or to receive no invitation or screening (the usual-care group). The primary end points were the risks of colorectal cancer and related death, and the secondary end point was death from any cause.

RESULTS: Follow-up data were available for 84,585 participants in Poland, Norway, and Sweden - 28,220 in the invited group, 11,843 of whom (42.0%) underwent screening, and 56,365 in the usual-care group. A total of 15 participants had major bleeding after polyp removal. No perforations or screening-related deaths occurred within 30 days after colonoscopy. During a median follow-up of 10 years, 259 cases of colorectal cancer were diagnosed in the invited group as compared with 622 cases in the usual-care group. In intention-to-screen analyses, the risk of colorectal cancer at 10 years was 0.98% in the invited group and 1.20% in the usual-care group, a risk reduction of 18% (risk ratio, 0.82; 95% confidence interval [CI], 0.70 to 0.93). The risk of death from colorectal cancer was 0.28% in the invited group and 0.31% in the usual-care group (risk ratio, 0.90; 95% CI, 0.64 to 1.16). The number needed to invite to undergo screening to prevent one case of colorectal cancer was 455 (95% CI, 270 to 1429). The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group (risk ratio, 0.99; 95% CI, 0.96 to 1.04).

CONCLUSIONS: In this randomized trial, the risk of colorectal cancer at 10 years was lower among participants who were invited to undergo screening colonoscopy than among those who were assigned to no screening. (Funded by the Research Council of Norway and others; NordICC ClinicalTrials.gov number, NCT00883792.).

Clinical Comments

Family Medicine (FM)/General Practice (GP)

As a GP, it is reassuring to see such a large study confirming that it is worth screening for bowel cancer using colonoscopy. However, it did not discuss in great detail the cost of the programme, which we need to know if Wilson's criteria are to be followed. It may be that with number needed to screen to save one life of > 450, the health care economists may have something to say.

Family Medicine (FM)/General Practice (GP)

Comparing colonoscopy to no screening, as in this study, would be hard to do now. It's reassuring that over 10 years the incidence was a little lower, and in those who actually agreed to get scoped, their colorectal cancer mortality was a bit lower. The number needed to treat over 10 years seems like a lot, though. As with almost everything else we do, total mortality was not different. Useful to use this for shared decision-making with patients.


Would emphasize some of the highlights of this study and also the limitations reported by the authors in the discussion. The findings in Europe may not be relevant in other countries for a variety of reasons (e.g., obesity in the US can be associated with a higher risk for colorectal cancer).


This is an important trial that provides direct proof of the value of colonoscopy in reducing CRC incidence and mortality. However, great care should be taken to place the results in appropriate context as the data are presented in a slightly biased way that under-value the benefits of colonoscopy. Please see the excellent accompanying editorial by Dominitz and Robertson in the same issue.


Highly controversial and worthy of highlighting.

Oncology - Gastrointestinal

As a radiation oncologist, I am not involved in screening studies. However, the results provide useful information for when I am asked by a patient's accompanying spouse/relative whether they might benefit from screening colonoscopy.

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