[Association between the uptake rates of countermeasure-type colorectal cancer screening, new cancer detection indices, and number of municipal public health nurses: An ecological study].

Objective　We conducted an ecological analysis of the structures and processes of municipalities implementing countermeasure-type colorectal cancer screening services, which are associated with high mortality and morbidity rates. We analyzed the populations' demographic characteristics, number of public health nurses (PHNs), and human base for such services. The process was evaluated using the screening uptake rates for countermeasure-type cancer screening and detection indices.Methods　The data included municipal population figures, areas, and national health insurance enrolments, all sourced from a government statistics portal (e-Stat). We obtained the number of PHNs per 100,000 population from PHN activity area surveys, information on municipal colorectal cancer screening from public health centers (PHCs) and health promotion project reports, and cancer detection indices from the National Cancer Registry data. The analysis covered 1,234 municipalities with populations of ≥10,000 and ≥50,000, categorized into three groups based on the presence of PHCs. The internal structures were compared using multiple regression analysis.Results　The number of PHNs per 100,000 population was categorized as follows; <50,000 population group (42.9), ≥50,000 population group (24.3), and PHC-present city group (16.4).Among these groups, the mass and individual screening rates were 96.2% and 47.7%, 69.1% and 91.5%, and 83.7% and 69.9%, respectively. The average uptake rates of countermeasure-type screenings and detailed examinations were 10.6-13.7% and 68.4-75.3%, respectively. In both cases, the <50,000 population and PHC-present city groups exhibited high and low values, respectively. However, the proportion of patients with "early cancer" detection was approximately 42% in all groups.Multiple regression analysis, using the countermeasure-type screening uptake rate and colorectal cancer detection indices as dependent variables, revealed that in the <50,000 population group, in which mass screening was prevalent, the number of PHNs was significantly positively correlated with the countermeasure-type screening uptake rate and proportion of "new cancers" detected by screening.Contrastingly, the PHC-present city group showed no correlation between the number of PHNs and countermeasure-type screening uptake rate, but a highly detailed examination uptake rate was significantly positively correlated with the proportion of "early cancer" detection.Conclusion　In municipalities without PHCs, countermeasure-type screening uptake rates, particularly mass screening rates, were positively correlated with the number of PHNs and cancer detection indices. In cities with PHCs, in which individual screening was prevalent, the detailed examination uptake rate through countermeasure-type screening was correlated with detection indices.