Mortality trends among U.S. adults with breast cancer and hypertensive diseases: A nationwide CDC WONDER analysis from 1999 to 2023.

e12716 Background: Hypertension is a well-established risk factor for cardiovascular mortality among cancer patients and may influence breast cancer outcomes through treatment-related cardiotoxicity, vascular remodeling, and systemic inflammation. Despite these interactions, national mortality trends among individuals with both breast cancer and hypertensive diseases have not been comprehensively characterized. This study evaluates long-term mortality patterns and demographic disparities in U.S. adults with coexisting breast cancer and hypertensive diseases from 1999 to 2023. Methods: Mortality data were extracted from the CDC WONDER Multiple Cause-of-Death database for 1999–2023 using ICD-10 codes corresponding to malignant neoplasm of the breast and hypertensive diseases. Age-adjusted mortality rates (AAMRs) per 100,000 population were calculated and stratified by sex, race and ethnicity, census region, age group, state, and urbanization level. Temporal trends were quantified using Joinpoint regression to estimate annual percent change (APC) and average annual percent change (AAPC) with 95% confidence intervals (CIs). Results: Mortality involving both breast cancer and hypertensive diseases increased markedly, with AAMRs rising from 1.65 in 1999 to 6.16 in 2023. A sharp rise began in 2018 (APC: 22.42%, 95% CI: 14.32–31.08). Across the entire period, the AAPC indicated a significant upward trend (5.08%, 95% CI: 3.32–6.86). Females exhibited higher mortality than males, although significant increases were observed in both groups after 2018. All census regions showed rising mortality, with the South experiencing the highest burden (AAPC: 6.45%). Significant post-2018 increases occurred across racial groups, with White and Black individuals reaching the highest absolute mortality levels by 2023. Mortality rose in both metropolitan and nonmetropolitan areas, while older adults (65+) demonstrated AAMRs nearly tenfold higher than middle-aged adults and a steep post-2018 surge (APC: 21.71%). Geographic disparities widened, with multiple states, including Oklahoma, Mississippi, Nebraska, Colorado, Wyoming, and the District of Columbia, entering the highest mortality percentile. Home was the most common place of death in both study periods. Conclusions: Mortality involving coexisting breast cancer and hypertensive diseases has accelerated significantly in the United States, particularly after 2018. These trends highlight the growing cardio-oncologic vulnerabilities and the need for targeted prevention.