Ovarian Function Suppression in HR-Positive, HER2-Positive Breast Cancer: An Exploratory Analysis of the HERA Trial

BACKGROUND: Data on the effectiveness of ovarian function suppression (OFS) in premenopausal patients with hormone receptor (HR)-positive, HER2-positive breast cancer are sparse. We investigated the prognostic impact of incorporating OFS in premenopausal women with HER-positive, HR-positive breast cancer, drawing on data from the HERceptin Adjuvant (HERA) trial. PATIENTS AND METHODS: We examined patient-level data from the HERA trial (BIG1-01) to assess whether adding OFS enhances disease-free survival (DFS) and overall survival (OS) in premenopausal women with early-stage HR-positive, HER2-positive breast cancer. Additionally, we explored differences in prognosis between types of oral antiestrogens, specifically tamoxifen (TAM) and aromatase inhibitors (AIs). RESULTS: A total of 965 patients were included in our analysis; 501 (51.9%) received TAM only, and 464 (48.1%) underwent endocrine therapy with OFS. The addition of OFS independently correlated with enhanced DFS (hazard ratio, 0.68; 95% CI, 0.53-0.87; P=.002) and OS (hazard ratio, 0.62; 95% CI, 0.44-0.85; P=.003). The 10-year DFS rates were 70.9% with OFS versus 59.6% with TAM only, whereas the 10-year OS rates were 84.7% with OFS versus 74.0% with TAM only. Among the patients treated with OFS, AI was associated with favorable survival outcomes compared with TAM. CONCLUSIONS: Our findings suggest that adding OFS to adjuvant endocrine therapy may improve survival outcomes in premenopausal women with HR-positive, HER2-positive breast cancer who are receiving chemotherapy and HER2-targeted therapy, and are at high risk of relapse. CLINICALTRIALS: gov identifier: NCT00045032.