BMRK-08 TRENDS IN BREAST CANCER BRAIN METASTASES INCIDENCE AND MORTALITY: DISPARITIES BY MOLECULAR SUBTYPES, AGE, AND RACE

Abstract Brain metastases represent a critical complication of breast cancer, with a significant impact on patient prognosis. Understanding the variations in incidence and mortality across molecular subtypes, races, and age groups is crucial to enhance risk stratification and guide resource allocation. Identifying these trends can inform treatment and prognostication efforts. Utilizing the Surveillance, Epidemiology, and End Results 17 database, this study examined trends in synchronous breast cancer brain metastasis (BCBM) incidence and mortality from 2010-2020. The National Cancer Institute’s Joinpoint Regression Program was employed to estimate annual percent changes (APCs). Results were considered significant if the 95% confidence interval excluded zero, and trends were identified using JoinPoint software to delineate variations across demographic and molecular distinctions. There was a significant overall increase in BCBM incidence (APC=2.3%) between 2010-2020. Analysis by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status revealed incidence increases across all four subtypes, with Non-White patients experiencing a significant decrease in BCBM incidence in HR-/HER2+ tumors (APC=-7.7%). After accounting for observation-time bias, mortality rates demonstrated statistically significant upward trends overall (APC=4.0%) and across several biomarker groups, particularly HR+/HER2+ (APC=7.3%), HR-/HER2+ (APC=5.6%), and HR+/HER2- (APC=4.4%). While the increase in HR-/HER2- was more modest (APC=2.7%), it contributes to the evolving landscape of BCBM mortality. Disparities in mortality rates were also pronounced among age and racial groups within these individual subtypes. Representing the largest population-based study to evaluate trends in BCBM incidence and mortality, our analysis uncovers varying patterns across molecular subtypes, age, and race. These disparities suggest underlying biological differences and inherent healthcare barriers, highlighting the urgent need for targeted interventions in at-risk populations. Our findings lay crucial groundwork for further research into these disparities and tailored clinical and policy measures to improve BCBM outcomes.