Racial and ethnic disparities in treatment-related heart disease mortality among US breast cancer survivors.

Background: Racial and ethnic disparities in heart disease mortality by initial treatment type among breast cancer survivors have not been well described.

Methods: We included 739 557 women diagnosed with first primary invasive breast cancer between 2000 and 2017 (aged 18-84 years, received surgery, survived ≥1 year, followed through 2018) in the Surveillance, Epidemiology, and End Results-18 database. Standardized mortality ratios (SMRs; observed over expected) were calculated by race and ethnicity (non-Hispanic/Latina Asian American, Native Hawaiians, and other Pacific Islanders [AANHPI]; non-Hispanic/Latina Black [Black]; Hispanic/Latina [Latina]; and non-Hispanic/Latina White [White]) and initial treatment (surgery only; chemotherapy with surgery; chemotherapy, radiotherapy, with surgery; and radiotherapy with surgery) compared with the racial- and ethnic-matched general population, and by clinical characteristics. Cumulative heart disease mortality was estimated accounting for competing risks.

Results: SMRs were elevated for Black and Latina women treated with surgery only and chemotherapy with surgery (SMR range = 1.15-1.21) and AANHPI women treated with chemotherapy, radiotherapy, with surgery (SMR = 1.29; 95% confidence interval [CI] = 1.11 to 1.48), whereas SMRs were less than 1 for White women (SMR range = 0.70-0.96). SMRs were especially high for women with advanced (regional or distant) stage among Black women for all treatment (range = 1.15-2.89) and for AANHPI and Latina women treated with chemotherapy with surgery (range = 1.28-3.61). Non-White women diagnosed at younger than age 60 years had higher SMRs, as did Black and AANHPI women diagnosed with estrogen receptor-positive breast cancers. Black women had the highest 10-year cumulative risk of heart disease mortality: aged younger than 60 years (Black: 1.78%, 95% CI = 1.63% to 1.94%) compared with White, AANHPI, and Latina women (<1%) and aged 60 years and older (Black: 7.92%, 95% CI = 7.53% to 8.33%) compared with White, AANHPI, and Latina women (range = 3.90%-6.48%).

Conclusions: Our findings illuminated striking racial and ethnic disparities in heart disease mortality among Black, AANHPI, and Latina breast cancer survivors, especially after initial chemotherapy receipt.