A nationwide ecological analysis of municipal factors affecting breast cancer screening participation during the COVID-19 pandemic in Japan

Screening is a key measure in the prevention of breast cancer; however, disparities exist in screening participation. The COVID-19 pandemic impacted screening programmes, but data from the Western Pacific region remain limited. This study examined factors associated with changes in breast cancer screening participation in Japanese municipalities during the COVID-19 pandemic. This ecological study used data from 1,707 Japanese municipalities. The dependent variable was the ratio of the 2020 to 2019 screening participation rates. The independent variables included 12 municipality-level factors related to population, finances, and medical resources. Correlation and multiple linear regression analyses were conducted to determine relationships. Significance was set at p < 0.05 (two-sided). Variables were rank-based inverse-normal transformed. The change in breast cancer screening participation was significantly associated with four municipality-level factors—population density, annual municipal expenditure per capita, hospital ratio, and the unemployment rate—in the final model including all independent variables. Notably, annual municipal expenditure per capita was positively associated (β = 0.188, p < 0.001) and the unemployment rate was negatively associated (β = − 0.081, p = 0.007) with the change in participation. The findings suggest that regional economic status is a key factor influencing breast cancer screening participation during a public health emergency. To address disparities in screening participation, it is important to focus on differences in how public health services are funded and provided. These findings offer insights for Japan and other countries that provide cancer screening through local administrations.