Does hormone receptor (HR) positivity affect the prognosis in breast cancers with human epidermal growth factor receptor 2 (HER2) overexpression?

Abstract

e22091 Background: Biologically, there is an unclear issue about the role of HR positivity in HER2 positive breast cancer. These HER2(+)/ HR(+) pts were grouped into luminal B type apart from HER2(+)/ HR(-) pts in molecular profiling. However, from the clinical point of view, these pts have been categorized and been treated as either the only HER2(+) disease regardless of HR status or vice versa. Thus, we investigated the impact of HR status on clinical outcomes in HER2-overexpressed breast cancers. Methods: We retrospectively reviewed medical charts of HER2-positive breast cancer pts who underwent curative surgical resection from 1996 to 2001 in the Severance hospital, Korea. Demographic comparisons were performed by Chi-square tests. Tumor size, nodal stage, TNM stage, HR status, and adjuvant tamoxifen use were included in the Cox proportional hazards model. Results: Among the total 174 HER2-positive pts, HR (n=93) was positive in 53.5% (n = 93) and HR-positive tumors were more likely to be premenopausal (73% v 52%; P=0.01) and well- differentiated (grade 1or 2; 77% v 62%; P=0.04). There were no significant differences according to HR status in terms of tumor size, nodal stage, TNM stage, operation methods, and chemotherapy regimen. In these HER2-positive pts, the 5-year disease free survival (DFS) was longer in HR(+) pts than in HR(-) pts (DFS; 82.9% v 61.5%; P= 0.01). In a subset analysis, the 5-year DFS of HER2(+)/ER(+) pts without adjuvant tamoxifen (n=26) was not different from that of HER2(+)/ ER(-) pts (DFS; 57.7% v 61.5%; P= 0.32). However, the 5-year DFS of HER2(+)/ ER(+) pts with adjuvant tamoxifen was significantly prolonged compared with that of HER2(+)/ ER(-) pts (DFS; 91.5% v 61.5%; P< 0.001). In a multivariate analysis of DFS, tumor size and adjuvant tamoxifen use significantly affected DFS with an adjusted hazard ratio of 2.56 (95% CI, 1.2–4.9; P= 0.01) and 6.58 (95% CI, 2.8–20.3; P< 0.001), respectively. Conclusions: In an analysis of HER2-overexpressed breast cancer, the presence of HR itself did not affect the prognosis. However, most of the survival benefit seems to be driven from adjuvant tamoxifen therapy not the HR status itself. No significant financial relationships to disclose.