Impact of Anti-Estrogen Therapy on Early Cardiovascular Referrals, Tests and Medications in Premenopausal Women with Operable Breast Cancer.

Introduction: Premenopausal women with high-risk hormone receptor (HR)-positive breast cancer often receive ovarian function suppression (OFS) and anti-estrogen therapy which induces near complete estrogen deprivation (NCED). This treatment improves recurrence-free survival but may increase cardiovascular risk. We sought to identify patterns of cardiovascular care and outcomes in premenopausal women with operable breast cancer.

Methods: Premenopausal women ≤ 50 years of age with stage I-III HR-positive or triple negative breast cancer (TNBC) were identified by retrospective review. We categorized women into 3 groups based on anti-estrogen therapy approach: NCED (HR + OFS), anti-estrogen therapy without OFS (HRnoOFS), and no anti-estrogen therapy (TNBC). Baseline characteristics, post-diagnosis cardiovascular events and cardiovascular actions (tests, referrals and medications) were recorded. Categorical variables were compared among the groups using chi-square and Fisher's exact tests; continuous outcomes were compared using ANOVA.

Results: 82, 83, and 52 women were identified in the HR + OFS, HRnoOFS, and TNBC groups respectively; mean follow-up was 5.0 years. Mean number of cardiovascular actions per year were highest in the HR + OFS group compared with HRnoOFS and TNBC groups (0.35 vs. 0.20 and 0.27, respectively; P = .036). The HR + OFS group had significantly more referrals and tests per year than the other groups. Cardiovascular medication initiation did not differ among groups.

Conclusions: In this early follow-up period, there were meaningful numbers of cardiovascular actions, with women on NCED experiencing the most per year. Future work should seek to further understand the impact of anti-estrogen therapy on the cardiovascular health of premenopausal women and test strategies to mitigate cardiotoxicity.