Abstract B055: Guideline-concordance along the cancer care continuum and breast cancer mortality by race and ethnicity: A SEER-Medicare study

Abstract Purpose. To examine the relationship between guideline-concordant breast cancer care and hazard of cancer death by patient race and ethnicity. Methods. We used SEER-Medicare data to identify 212,555 older women diagnosed with invasive breast cancer between 2000-2017. Guideline-concordant diagnostic workup, locoregional treatment, and initiation of systemic therapy were defined using NCCN guidelines. Hazards of breast cancer death 2- and 5-years from diagnosis by each guideline-concordance outcome overall and stratified by race and ethnicity were estimated using Cox proportional hazards models. Results. Non-concordant diagnostic workup, locoregional treatment, and systemic therapy initiation were each associated with increased hazards of 2- and 5-year breast cancer mortality (diagnostics HR2-year (95% CI) 1.33 (1.25-1.41), HR5-year 1.29 (1.23-1.35); locoregional HR2-year 2.18 (2.10-2.30), HR5-year 1.85 (1.78-1.92); systemics HR2-year 1.62 (1.50-1.80), HR5-year 1.51 (1.42-1.62)). Non-concordant diagnostic workup and systemic therapy initiation were associated with greater hazard of 2- and 5-year breast cancer death among Black, Asian/Pacific Islander, Hispanic White, and non-Hispanic White patients; there was no consistent association among American Indian/Alaska Native patients for either outcome. Locoregional treatment was strongly associated with hazards of cancer death for all groups. Conclusions. Equitable delivery of guideline-recommended breast cancer care from diagnosis through treatment across racial and ethnic groups may mitigate survival disparities. Efforts to improve access to high-quality care must be informed by and responsive to the social and structural root causes of health inequities. Citation Format: Emma L. Herbach, Ryan M. Carnahan, Lauren E. McCullough, Bradley D. McDowell, Michaela Curran, Kai Wang, Ingrid M. Lizarraga, Mary E. Charlton, Sarah H. Nash. Guideline-concordance along the cancer care continuum and breast cancer mortality by race and ethnicity: A SEER-Medicare study [abstract]. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr B055.