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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.