Forecasting colorectal cancer screening in Japan: regional and sex disparities threaten national targets.

OBJECTIVE

To forecast prefecture-level progress toward Japan's 60% colorectal cancer (CRC) screening target by 2028 and quantify regional and sex-based disparities.

METHODS

We extracted CRC screening rates (ages 40-69) for all 47 prefectures from 2013 to 2022 using the Comprehensive Survey of Living Conditions. Sex-stratified Bayesian linear regression models were applied to logit-transformed rates. Prefectures were considered likely to achieve the target if the probability of ≥ 60% uptake by 2028 was ≥ 80%.

RESULTS

Nationwide coverage is projected to reach 51.9% (95% CrI 44.9-58.8%) by 2028, falling 8.1 percentage points short of the 60% target. Forty of 47 prefectures (85%) had less than a 20% posterior probability of meeting the target, and 14 were projected below 50% coverage. Only Yamagata exceeded the 80% probability threshold for the total population (probability 0.988). For men, three prefectures did (Yamagata, Yamanashi, Miyagi), versus one for women. Men outperformed women in 41 of 47 prefectures, with a median sex gap in target probability of 8.0 percentage points and a median lag of 6 years in projected achievement.

CONCLUSIONS

Based on 2013-2022 trends, Japan is projected to miss the 60% CRC screening target by over a decade. Most prefectures had less than a 5% estimated probability of reaching 60% by 2028, and women lag men by a median of 6 years. Incremental progress under the current system appears insufficient. Reaching the target will require accelerated, prefecture-specific, and sex-sensitive interventions beyond what the current system delivers.