Breast cancer mortality by age and race and/or ethnicity across counties in the United States, 2000-2019

BACKGROUND: We evaluated county-level variations in racial and/or ethnic disparities in breast cancer mortality rates across the U.S. over a 20-year period. METHODS: Validated small-area estimation models were used to calculate breast cancer mortality rates by age and race and/or ethnicity among females across all U.S counties from 2000 to 2019. The estimates were corrected for misreporting of race and/or ethnicity on death certificates and age-standardized to the 2010 U.S. Census. RESULTS: Age-standardized national breast cancer mortality rates declined between 2000 to 2019, from 33.6 (95% Uncertainty Interval 33.4 to 33.9) to 24.8 (24.6 to 25.0) deaths per 100,000 females. However, there were variations in breast cancer mortality rates across racial and/or ethnic populations at the county level. For instance, 243 of 1,478 counties showed increasing breast cancer mortality rates from 2000 to 2019 among Latina females aged <50 years (absolute increase (median): 0.23 deaths per 100,000; maximum: 1.0). County-level patterns for American Indian/Alaska Native females aged 50 to 74 years showed increasing breast cancer mortality rates across 108 of 474 counties (median: 4.4 per 100,000; max: 17.5). The largest county-level increases were seen among American Indian/Alaska Native (184 of 474 counties; median: 15.2 per 100,000; max: 124.0) and Asian (589 of 667 counties; median: 14.1 per 100,000, max: 41.0) females aged ≥75 years. CONCLUSIONS: Despite a substantial decrease in overall breast cancer mortality rates across all female populations combined in the U.S., there were significant county-level variations in breast cancer mortality rates by race and/or ethnicity.