Geographical clusters of U.S. counties with significant high or low breast cancer incidence rates among Caucasians (including Hispanics) analyzed at a 200 km distance band. The graduated red and blue colors show high (hot) and low (cold) clusters respectively, for age-adjusted average annual incidence rates (2000/2001-2004/2005) of breast cancer. The counties with no color either have no data or counts less than 3-5. Graduated colors were assigned to the hot and cold clusters based on the incidence rate of individual counties. In total there were 2,692 counties used in the breast cancer cluster analysis. The inserted regional U.S. map depicts the regions of the U.S. used to describe the cluster patterns. Data source: National Cancer Institute-State Cancer Profiles and State Cancer Registries.