Differences and similarities in breast and colorectal screening participation: a spatial and temporal analysis to reveal intervention areas, France

Objective: Although breast and colorectal cancers are included in organized screening programs, participation remains suboptimal and influencing factors have evolved. We present a reproducible method for visualizing the spatiotemporal patterns of participation in these screening programs. Methods: The study includes breast and colorectal screening participation rates for women aged 50-74 years across 751 census blocks residing in the Rhône and Lyon metropolitan areas. Over two periods (pre, 2015-2019 and post, 2020-2022 pandemic), this ecological study allowed the creation of strategic maps to identify local priority areas for interventions. A spatial statistic Local Moran's I was used to identify clusters of high and low participation in both periods. These results were combined to map temporal evolution, classifying census blocks as consistently high, low, improved, or worsened in participation. Contextual factors have helped to describe these trends. Results: Maps revealed clear spatial disparities. For colorectal screening, participation increased by about 5 percentage points, from 33% to 38%, while breast screening remained stable at around 49%. In Lyon metropole, low-income census blocks with good healthcare access exhibited persistently low participation in both screenings. In the Rhône area, participation improved over time, and healthcare providers availability appeared to be a key determinant. Conclusions: This approach visualizes screening participation across space and time, providing a tool for policymakers to identify areas requiring intervention and adapt prevention strategies to local contexts.