Racial Disparity in Microvascular Function among Women with Newly Diagnosed Breast Cancer.

Abstract

BACKGROUND: Cardiovascular disease (CVD) is a leading cause of death in women with breast cancer, with non-Hispanic Black (NHB) women experiencing higher CVD-related mortality compared to non-Hispanic White (NHW) women. Differences in vascular health may contribute to this disparity. This study assessed cardiovascular health in NHB and NHW women with breast cancer. METHODS: Forty-five women (25 NHW, 20 NHB) within two years of diagnosis (AJCC stages 0-3) participated. Clinical labs, senescence-associated secretory phenotype (SASP), and allostatic load were assessed. Flow-mediated dilation (FMD) assessed conduit vessel function; cutaneous post-occlusive reactive hyperemia (PORH), local thermal heating (LTH), and iontophoresis of acetylcholine (Ach) assessed microvascular function. Pulse wave velocity (PWV) and pulse wave analysis (PWA) measured arterial and aortic stiffness, respectively. Maximal exercise testing (VO₂ peak) and near-infrared spectroscopy assessed skeletal muscle oxidative capacity (SMOC). RESULTS: Participants enrolled 6±5 months after diagnosis. Chemotherapy exposure (p=0.897) and cancer stage (p=0.382) were not different between groups. NHW women were older (59±12 vs. 53±12 years; p=0.090), but BMI, clinical labs, SASP, and allostatic load did not differ (all p>0.05). NHW women demonstrated higher PORH (p<0.001), LTH (p<0.001), and Ach responses (p=0.033), which remained significant after adjusting for cancer stage and chemotherapy. No differences were seen in FMD, PWV, PWA, VO₂₂ peak, or SMOC. CONCLUSION: NHB women with breast cancer exhibited impaired microvascular function compared to NHW women, independent of social determinants, cancer stage, or chemotherapy. These findings suggest microvascular dysfunction may contribute to racial disparities in CVD risk after breast cancer diagnosis.