The 13-year follow-up of the NORDICC randomized trial found that a single screening colonoscopy reduced colorectal cancer incidence but did not demonstrate a statistically significant reduction in CRC mortality. Among 28,217 participants assigned to screening and 56,366 assigned to no screening, CRC incidence was 1.46% vs 1.80% (ITT RR, 0.81; 95% CI, 0.71–0.90), while CRC mortality was 0.41% vs 0.47% (ITT RR, 0.88; 95% CI, 0.68–1.08). Only 42% of those assigned to screening actually underwent colonoscopy.
The per-protocol analysis showed a larger reduction in CRC incidence (RR, 0.55), and the benefit appeared greater in men than women. Gastroenterologist Aasma Shaukat noted that the trial is important because previous estimates of colonoscopy’s benefit largely came from observational studies, and the findings suggest the underlying CRC incidence and mortality of a population may influence the benefit achievable through screening.