Cardiovascular disease mortality among women diagnosed with de novo metastatic breast cancer

Women with metastatic breast cancer (mBC) are living longer than in prior decades due to advances in treatment. However, risk of cardiovascular disease (CVD) remains understudied in this patient population.

We identified 33,239 women diagnosed with de novo mBC between 2000 and 2020 (aged 20-84, survived ≥1 year) from 17 Surveillance, Epidemiology, and End Results Program registries. We estimated standardized mortality ratios (SMRs) and cumulative incidence, accounting for competing risks, for CVD mortality overall and by key characteristics.

Over 3.1 median years of follow-up, 724 women with mBC died of CVD (554 heart disease; 127 cerebrovascular disease; 43 other CVD). Overall, women with mBC had an elevated risk of CVD mortality compared to women in the general population after accounting for age, year, and race/ethnicity (SMR=1.45, 95 % CI=1.34-1.55). SMRs for women with mBC were further elevated among those aged < 50 years at diagnosis (3.48, 95 % CI=2.67-4.46), non-Hispanic Asian American and Pacific Islander and Black women (2.18, 95 % CI=1.60-2.90; 2.14, 95 % CI=1.79-2.52, respectively), more recently diagnosed women (1.57, 95 % CI=1.32-1.86), and those with triple negative tumors (2.51, 95 % CI=1.71-3.57). Among women aged < 50 years, SMRs were further elevated among those recently diagnosed (5.44, 95 % CI=2.90-9.31) and within the first five years after diagnosis (5.02, 95 % CI=3.63-6.76). Approximately 1 in 60 women died from CVD within five years following their mBC diagnosis (cumulative incidence: 1.73 %, 95 % CI=1.58-1.88 %) with the highest cumulative incidence among those aged 50 years or older (2.13 %, 95 % CI=1.95-2.33 %).

Women with mBC have significantly elevated CVD mortality and further research is warranted to address this heightened risk.