Proportion of Screen‐Detected Gastrointestinal Cancers From the National Cancer Registry in Japan

Historically, information on routes of diagnosis in cancer registration in Japan lacked reliability. The launch of the National Cancer Registry in 2016 produced a marked improvement in data accuracy. In this study, we aimed to estimate the proportion of screen-detected gastrointestinal cancers using the National Cancer Registry and to examine its correlation with cancer screening participation rates. We analyzed 2016-2020 National Cancer Registry data to identify screen-detected gastrointestinal cancers and assess the correlation between route of diagnosis and stage at diagnosis. Screening participation rates were extracted from the Comprehensive Survey of Living Conditions (CSLC) and the Report on Regional Public Health Services and Health Promotion Services via e-Stat, and their correlations with screen-detected cancer proportions were assessed using prefecture-level data. Screen-detected cancers accounted for 14.4% for esophageal cancer, 18.6% for gastric cancer, and 21.3% for colorectal cancer. Cancers detected through "other routes (including symptomatic detection)" accounted for 47.1%, 41.6%, and 45.1%, respectively. Screen-detected cases more frequently presented as intraepithelial or localized disease. In gastric and colorectal cancer, positive correlations were observed between the proportions of screen-detected cancers and screening participation rates; for example, correlation coefficients based on the 2019 CSLC were 0.61 for gastric cancer and 0.71 for colorectal cancer. Screen-detected gastrointestinal cancers accounted for roughly 20% of all detected routes. Higher screening rates were correlated with higher proportions of screen-detected cancers. These findings suggest that the proportion of screen-detected cancers may serve as an indicator of screening program quality.