NordICC
NordICC: The Northern-European Initiative on Colorectal Cancer
N = 84,585NCT00883792
- Population
- Presumptively healthy people aged 55 to 64 years; follow-up data were available for 84,585 participants in Poland, Norway and Sweden.
- Design
- Pragmatic randomised trial; presumptively healthy men and women aged 55 to 64 drawn from population registries in Poland, Norway, Sweden and the Netherlands between 2009 and 2014 were randomly assigned 1:2 to an invitation to a single screening colonoscopy or to no invitation or screening (usual care). Primary end points were the risks of colorectal cancer and related death; the secondary end point was death from any cause. The primary report analyses follow-up data from Poland, Norway and Sweden.
- Primary endpoint
- Colorectal cancer incidence, Colorectal cancer mortality
- Arms
- Invited to colonoscopy (experimental, n = 28,220): Invitation to a single screening colonoscopy
- Usual care (control, n = 56,365): No invitation and no screening
- People
- Bretthauer M
Δ Colorectal cancer incidence−0.22 pointsΔ Colorectal cancer mortality−0.03 pointsΔ All-cause mortality−0.01 points
Show the numbers
| Endpoint | Analysis | Invited to colonoscopy | Usual care | Effect |
|---|---|---|---|---|
| Colorectal cancer incidenceIntention-to-screen analysis (Poland, Norway, Sweden)Risk of colorectal cancer at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 0.98% | 1.2% | Intention-to-screen risk ratio 0.82 (95% CI 0.70 to 0.93), an 18% risk reduction; 259 cases in the invited group and 622 in the usual-care group; number needed to invite to prevent one case of colorectal cancer 455 (95% CI 270 to 1429). Risk ratio, not a hazard ratio. |
| Colorectal cancer mortalityIntention-to-screen analysis (Poland, Norway, Sweden)Risk of death from colorectal cancer at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 0.28% | 0.31% | Intention-to-screen risk ratio 0.90 (95% CI 0.64 to 1.16); the interval includes 1, so the difference was not statistically significant. Risk ratio, not a hazard ratio. |
| All-cause mortalityIntention-to-screen analysis (Poland, Norway, Sweden)Risk of death from any cause at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 11.03% | 11.04% | Risk ratio 0.99 (95% CI 0.96 to 1.04). Secondary end point. Risk ratio, not a hazard ratio. |
| Colorectal cancer mortalityPer-protocol effect among people who were screened, estimated by instrumental-variable analysis (participation 42%)Risk of death from colorectal cancer at 10 years, per-protocol effect estimated by instrumental-variable analysis | exploratoryShi 2025 | — | 0.29% (0.24–0.33%) | In screened individuals the estimated 10-year risk was 0.20% (95% CI 0.09 to 0.73) to 0.22% (95% CI 0.08 to 0.37) depending on assumptions, giving risk ratios of 0.71 (95% CI 0.31 to 2.89) to 0.79 (95% CI 0.24 to 1.42). Every interval includes 1. The authors state their earlier per-protocol estimates may be affected by residual confounding, and that the validity of these estimates rests on a different set of assumptions. |
| Colorectal cancer incidencePer-protocol effect among people who were screened, estimated by instrumental-variable analysis (participation 42%)Risk of colorectal cancer at 10 years, per-protocol effect estimated by instrumental-variable analysis | exploratoryShi 2025 | — | 1.13% (1.04–1.23%) | In screened individuals the estimated 10-year risk was 0.66% to 0.74% (95% CI 0.57 to 0.95 for the upper estimate) depending on assumptions, giving risk ratios of 0.59 (95% CI 0.30 to 0.98) to 0.65 (95% CI 0.48 to 0.87). The authors summarise this as a 35 to 41% reduction in incidence at 10 years. |
| Endpoint | Analysis | Invited to colonoscopy | Usual care | Effect |
|---|---|---|---|---|
| Colorectal cancer incidenceIntention-to-screen analysis (Poland, Norway, Sweden)Risk of colorectal cancer at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 0.98% | 1.2% | Intention-to-screen risk ratio 0.82 (95% CI 0.70 to 0.93), an 18% risk reduction; 259 cases in the invited group and 622 in the usual-care group; number needed to invite to prevent one case of colorectal cancer 455 (95% CI 270 to 1429). Risk ratio, not a hazard ratio. |
| Colorectal cancer mortalityIntention-to-screen analysis (Poland, Norway, Sweden)Risk of death from colorectal cancer at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 0.28% | 0.31% | Intention-to-screen risk ratio 0.90 (95% CI 0.64 to 1.16); the interval includes 1, so the difference was not statistically significant. Risk ratio, not a hazard ratio. |
| All-cause mortalityIntention-to-screen analysis (Poland, Norway, Sweden)Risk of death from any cause at 10 years | primarymedian follow-up 10 yearsBretthauer 2022 | 11.03% | 11.04% | Risk ratio 0.99 (95% CI 0.96 to 1.04). Secondary end point. Risk ratio, not a hazard ratio. |
| Colorectal cancer mortalityPer-protocol effect among people who were screened, estimated by instrumental-variable analysis (participation 42%)Risk of death from colorectal cancer at 10 years, per-protocol effect estimated by instrumental-variable analysis | exploratoryShi 2025 | — | 0.29% (0.24–0.33%) | In screened individuals the estimated 10-year risk was 0.20% (95% CI 0.09 to 0.73) to 0.22% (95% CI 0.08 to 0.37) depending on assumptions, giving risk ratios of 0.71 (95% CI 0.31 to 2.89) to 0.79 (95% CI 0.24 to 1.42). Every interval includes 1. The authors state their earlier per-protocol estimates may be affected by residual confounding, and that the validity of these estimates rests on a different set of assumptions. |
| Colorectal cancer incidencePer-protocol effect among people who were screened, estimated by instrumental-variable analysis (participation 42%)Risk of colorectal cancer at 10 years, per-protocol effect estimated by instrumental-variable analysis | exploratoryShi 2025 | — | 1.13% (1.04–1.23%) | In screened individuals the estimated 10-year risk was 0.66% to 0.74% (95% CI 0.57 to 0.95 for the upper estimate) depending on assumptions, giving risk ratios of 0.59 (95% CI 0.30 to 0.98) to 0.65 (95% CI 0.48 to 0.87). The authors summarise this as a 35 to 41% reduction in incidence at 10 years. |
Appears in
Sources
Bretthauer M, Løberg M, Wieszczy P, Kalager M, Emilsson L, Garborg K, et al. Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death. N Engl J Med. 2022;387(17):1547-1556.
Shi J, Løberg M, Kalager M, Wieszczy P, Pilonis ND, Adami HO, et al. Effect of colonoscopy screening on risks of colorectal cancer and related death: instrumental variable estimation of per-protocol effects. Eur J Epidemiol. 2025;40(4):419-425.