Holme O, et al. - The authors aimed at ascertaining the effects of flexible sigmoidoscopy screening on colorectal cancer (CRC) incidence and mortality in women and men after 15 years of follow-up. In Norway, reduced CRC incidence and mortality in men was noted in association with offering sigmoidoscopy screening but the screening had little or no effect in women.

Methods

• Researchers performed a randomized controlled trial at Oslo and Telemark County, Norway .
• They included adults aged 50 to 64 years at baseline without prior CRC.
• Intervention included screening (between 1999 and 2001) with flexible sigmoidoscopy with and without additional fecal blood testing vs no screening.
• Colonoscopy was offered to participants with positive screening results.
• They assessed age-adjusted CRC incidence and mortality stratified by sex.

Results

• Researchers randomly assigned 20,552 to screening and 78,126 to no screening among the 98,678 persons.
• Adherence rates were 64.7% and 61.4% in women and men, respectively.
• They followed up the individuals for a median period of 14.8 years.
• In women, the absolute risks for CRC were 1.86% in the screening group and 2.05% in the control group (risk difference, -0.19 percentage point [95% CI, -0.49 to 0.11 percentage point]; HR, 0.92 [CI, 0.79 to 1.07]).
• The corresponding risks in men were 1.72% and 2.50%, respectively (risk difference, -0.78 percentage point [CI, -1.08 to -0.48 percentage points]; hazard ratio [HR], 0.66 [CI, 0.57 to 0.78]) (P for heterogeneity = 0.004).
• In women, the absolute risks for death of CRC were 0.60% in the screening group and 0.59% in the control group (risk difference, 0.01 percentage point [CI, -0.16 to 0.18 percentage point]; HR, 1.01 [CI, 0.77 to 1.33]).
• In men, the corresponding risks for death of CRC were 0.49% and 0.81%, respectively (risk difference, -0.33 percentage point [CI, -0.49 to -0.16 percentage point]; HR, 0.63 [CI, 0.47 to 0.83]) (P for heterogeneity = 0.014).