Sigmoidoscopy Screening Significantly Reduces Colorectal Cancer Risk in Men, suggests study
A new study published in the Annals of Internal Medicine journal showed that over a 23-year follow-up period, a once-only sigmoidoscopy screening program in Norway was linked to a 28% decrease in colorectal cancer (CRC) incidence and a 37% decrease in CRC deaths among males.
Sigmoidoscopy screening lowers CRC incidence and mortality for 15 years, according to meta-analyses of randomized studies. A single screening intervention produces very long-lasting clinical protection, as this historic Norwegian experiment shows. The inhabitants of Oslo and Telemark County, Norway, participated in the randomized controlled Norwegian Colorectal Cancer Prevention (NORCCAP) experiment.
Participants between the ages of 50 and 64 who were clear of CRC at the time of randomization were included in the trial. Participants were divided into an intervention group that had a single sigmoidoscopy, either with or without the inclusion of a single fecal immunochemical test, or a control group that had no screening to assess the effectiveness of various screening strategies. The incidence of colorectal cancer and CRC-related death were the main outcomes monitored during the experiment.
98,654 individuals (20 552 in the screening group and 78 102 in the no-screening group) were included in intention-to-screen analyses out of the 1,00,210 individuals who were randomly allocated. 61.4% of males and 64.7% of women participated in the screening. Men's 23-year cumulative risk for colorectal cancer (CRC) was 4.3% in the screening group and 6.0% in the no-screening group.
This is a risk difference of −1.7 percentage points (95% CI, −2.2 to −1.2 percentage points). The comparable risks for women were 4.2% and 4.7%, resulting in a risk difference of -0.5 percentage points (CI, -1.0 to -0.01 percentage points). Men in the screening group had a 23-year cumulative risk of dying from colorectal cancer (CRC) of 1.4%, whereas those in the no-screening group had a risk difference of −0.8 percentage points (CI, −1.1 to −0.5 percentage points).
The comparable risks for women were 1.3% and 1.4%, resulting in a −0.1 percentage point (CI, −0.3 to 0.1 percentage points) risk difference. Rectosigmoid carcinoma was most affected. The advantages of screening were unchanged when fecal blood tests were added to sigmoidoscopy. Overall, providing sigmoidoscopy screening decreased CRC mortality only in males and decreased CRC incidence more in men than in women.
Source:
Botteri, E., Holme, Ø., Løberg, M., Bretthauer, M., Kalager, M., Randel, K. R., & Hoff, G. (2026). Twenty-three-year benefits of sigmoidoscopy screening for colorectal cancer : A randomized trial: A randomized trial. Annals of Internal Medicine, ANNALS-25-05456. https://doi.org/10.7326/ANNALS-25-05456
