Sex variation in colorectal cancer mortality: trends and implications for screening

Colorectal cancer (CRC) screening using faecal tests reduces disease-specific mortality. To investigate mortality and its association with sex, rates in women and men, and in different age ranges, were examined, before and after screening began in Scotland.

From 1990-99, no structured screening existed. Three pilots ran from 2000 to 2007 and subsequent full roll-out completed in 2009. Crude mortality rates for 1990-2020 were calculated relative to Scottish population estimates, and age-sex standardized rates calculated for all, pre-screening (<50 years), screening (5-74 years) and post-screening (>74 years) age ranges.

CRC mortality declined from 1990 to 2020, but not linearly, and differed between sexes. In women, 1990-99 showed a steady decline [average annual percentage change (AAPC): -2.1%, 95% confidence interval (CI): -2.8% to -1.4%], but a less marked decline after 2000 (AAPC: -0.7%, 95% CI: -0.9% to -0.4%). In men, no clear decline was seen from 1990 to 1999 (AAPC: -0.4%, 95% CI: -1.1% to 0.4%), but mortality declined from 2000 to 2020 (AAPC: -1.7%, 95% CI: -1.9% to -1.5%). This pattern was exaggerated in the screening age ranges. For 2000-20, the overall reduction in mortality was less in women and in the screening age range. In the post-screening age range, reductions were smaller, but an increase was seen in the pre-screening age range, greater in women.

CRC mortality fell during 1990-2020, but the decline differed markedly between sexes, indicating a larger beneficial effect of screening on CRC mortality in men compared to women: use of different thresholds for the sexes might lead to equality.