ERBB2 and breast cancer: <h4>Introduction</h4>Adjuvant endocrine therapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer improves survival but may worsen cardiometabolic health; the cardiovascular impact of aromatase inhibitor plus ovarian function suppression (AI+OFS) in premenopausal women remains unclear.