Black and White disparity in U.S. female breast cancer mortality: a nationwide analysis, 1999-2023.

[OBJECTIVES] To comprehensively characterize the evolution of racial disparities in U.S. female breast cancer mortality between non-Hispanic Black and White women from 1999 to 2023 across age, geography, and urbanization levels.

[METHODS] We analyzed nationwide mortality data from the CDC WONDER database for women aged ≥ 25 years. We calculated age-adjusted mortality rates (AAMRs), absolute rate differences (ARD), and age-standardized rate ratios (ASRR). Joinpoint regression was employed to quantify temporal trends and identify significant changes over the 25-year period.

[RESULTS] Between 1999 and 2023, AAMRs declined for both Black (Average Annual Percent Change [AAPC] = -1.38, 95% CI -1.45 - -1.30) and White (AAPC = -1.46, 95% CI -1.56 - -1.35) women; however, Black women consistently experienced higher mortality. Disparity trends exhibited significant heterogeneity. While the mortality gap narrowed for women aged ≥ 55, the relative disparity for younger women (< 55 years) remained stagnant (ASRR ~ 1.88) despite absolute rate declines. Geographically, the Midwest achieved the most significant reduction in ARD. In contrast, the Northeast showed widening relative disparities. Notably, Massachusetts experienced a "disparity reversal," shifting from a Black survival advantage in 1999 to a significant mortality disadvantage by 2023. Additionally, disparities worsened in Large Fringe Metro areas compared to other urbanization levels.

[CONCLUSION] Despite national progress in reducing breast cancer mortality, racial equity remains elusive. The persistent gap among younger women and the widening disparities in specific "hotspot" regions and traditionally affluent states challenge the assumption that general healthcare improvements benefit all populations equitably, underscoring the urgent need for targeted, precision-based public health interventions.