Top Line: Has anyone not been inundated with incendiary one-liners on results from the NordICC trial?
The Study: Spoiler alert: it’s poised to put a damper on colon cancer walks everywhere. In the huge phase 3 NordICC trial—and we mean huge in a way the US could never dream of— citizens of Poland, Norway, Sweden, and the Netherlands were randomized 1:2 to be invited or not invited to a one-time colonoscopy screening between 2009 and 2014. After this screening event, they underwent surveillance according to national guidelines. With prospective follow-up data on 85,585 people, the risk of colorectal cancer at 10 years was significantly lower in the invited group (0.98% v 1.20%, 18% relative reduction). However, this did not translate to a significant reduction in colorectal cancer death at 10 years (0.28% v 0.31%, RR 0.90; 95% CI 0.64-1.16). In other words, screening (or rather intending to screen) tens of thousands of people presumably at the cost of many millions of dollars achieved an underwhelming 0.03% absolute reduction (10% relative reduction) in the risk of colon cancer death. Furthermore, the secondary endpoint of risk of death from any cause was identical in each group (11.03-11.04%). A big caveat is that just 42% of those invited to screen actually went through with a colonoscopy (ranging from 33% in Poland to 60.7% in Norway). Therefore, it is possible that the trial underestimated the true benefit of screening. In a per-protocol analysis of patients who actually underwent screening, there was a 31% relative reduction in colorectal cancer risk (0.84% v 1.22%) and a 50% relative reduction in colorectal cancer death (0.15% v 0.30%). Is this how colonoscopy screening performs in the real world? In one sense, NordICC shows us how effective invitations to participate in colonoscopy screening are at reducing the risk of colorectal cancer incidence and death. In another sense, it also suggests a benefit to screening in those who actually participate.
TBL: When less than half of patients invited for colonoscopy screening actually show up, there is only a modest reduction in colorectal cancer risk and no reduction in colorectal cancer mortality.
- Bretthauer, N Engl J Med 2022