Abstract PR009: Role of treatment on racial and ethnic disparities in heart disease mortality among U.S. breast cancer survivors, 2000-2018

Abstract Background: Breast cancer survivors have an elevated risk of dying from heart disease, in part due to cardiotoxic cancer treatment, such as chemotherapy and radiotherapy. Differences in heart disease mortality by race/ethnicity and initial treatment receipt among U.S. breast cancer survivors have not been well described. Methods: We calculated standardized mortality ratios (SMRs; observed/expected) for heart disease among 739,557 first primary breast cancer survivors (diagnosed between 2000-2017; aged 18-84 years; survived 12+ months) in the U.S. Surveillance, Epidemiology, and End Results 18 registries, compared to the racial/ethnic matched general population. Analyses were examined by race/ethnicity: non-Hispanic White (White), non-Hispanic Black (Black), non-Hispanic/Latina Asian, Native Hawaiians, and Pacific Islanders (AANHPI), and Hispanic/Latina (Latina), and initial treatment: surgery only, chemotherapy alone, chemotherapy plus radiotherapy, and radiotherapy alone. SMRs were stratified by stage (localized/regional/distant), age at breast cancer diagnosis (<60, ≥60 years), and estrogen receptor (ER) status (positive/negative). P-heterogeneity was calculated with multivariable adjusted Poisson regression models and likelihood ratio tests. We estimated 10-year cumulative heart disease mortality, accounting for competing risks (i.e., non-heart disease deaths), by race/ethnicity and age at breast cancer diagnosis. Results: SMRs for heart disease mortality among breast cancer survivors varied by race/ethnicity (p-heterogeneity<0.05) and initial treatment; SMRs were elevated for Black and Latina women treated with surgery only and chemotherapy alone (range: 1.15-1.21) and AANHPI women treated with chemotherapy plus radiotherapy (SMR: 1.29, 95%CI: 1.11,1.48), whereas for White women, SMRs were <1.00 for all treatment (range: 0.70-0.96). SMRs were especially high for women with advanced (regional or distant stage) disease among Black women for all treatment (range: 1.15-2.89), and for AANHPI and Latina women treated with chemotherapy only (range: 1.28-3.61). Non-white women diagnosed at age <60 years had higher SMRs, as did Black and AANHPI women diagnosed with ER positive breast cancers. Black women had the highest ten-year cumulative risk of heart disease mortality: age <60 years (Black: 1.78%, 95%CI:1.63%,1.94%) compared to White, AANHPI, and Latina women (all <1%); and age 60+ years: Black (7.92%, 95%CI:7.53%,8.33%) compared to White, AANHPI, and Latina women (range: 3.90%-6.48%). Conclusions: Our findings illuminated striking disparities in heart disease mortality among Black, Latina, and AANHPI breast cancer survivors, especially after initial chemotherapy, and these disparities persisted across clinical characteristics. Future studies are needed to examine racial/ethnic disparities by detailed cancer treatment (including chemotherapy and targeted agents, endocrine therapy, and radiation dose) and lifestyle risk factors. Citation Format: Jacqueline B. Vo, Cody Ramin, Wayne Lawrence, Ana Barac, Katherine Ho, Jongeun Rhee, Lene H.S. Veiga, Amy Berrington de Gonzalez. Role of treatment on racial and ethnic disparities in heart disease mortality among U.S. breast cancer survivors, 2000-2018 [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PR009.