Clinicopathological differences and survival benefit in ER+/PR+/HER2+ vs ER+/PR-/HER2+ breast cancer subtypes.

ABSTRACT

INTRODUCTION: Breast cancer subtypes based on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression have significant implications for prognosis. HER2-positive tumors historically demonstrated poorer survival, but anti-HER2 targeted therapy improved outcomes. However, hormone receptor (HR)-positive patients may experience reduced benefit due to HER2-HR signaling crosstalk. METHODS: Data from two databases, the Shanghai Jiao Tong University Breast Cancer Data Base (SJTUBCDB) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, were analyzed. Propensity score adjustments were used to balance patient characteristics between ER+/PR+/HER2+ and ER+/PR-/HER2+ subtypes. Kaplan-Meier survival curves estimated disease-free survival (DFS), breast cancer-specific survival (BCSS), overall survival (OS) for these subtypes in the SJTUBCDB, while subgroup analyses using multivariable models were performed based on menstruation, pN stage, HER2-targeted therapy, and endocrinotherapy. RESULTS: The ER+/PR+/HER2+ group showed significantly better DFS and BCSS than the ER+/PR-/HER2+ group, particularly in postmenopausal and pN0 stage patients. Survival outcomes were similar after anti-HER2 therapy or endocrine aromatase inhibitor (AI) therapy in both groups. However, among patients receiving selective estrogen receptor modulator (SERM) treatment, those in the ER+/PR-/HER2+ group had a significantly worse prognosis compared to ER+/PR+/HER2+ patients. CONCLUSIONS: HER2-positive breast cancers with different HR statuses exhibit distinct clinicopathological features and survival outcomes. Patients in the ER+/PR+/HER2+ group generally experience better survival, particularly in postmenopausal and pN0 stage patients. Treatment strategies should consider HR status and specific modalities for better personalized management.