HER2-Low Status Was Associated With Better Breast Cancer-Specific Survival in Early-Stage Triple-Negative Breast Cancer.

ABSTRACT

BACKGROUND: Based on the association between the hormone receptor and the status of human epidermal growth factor receptor 2 (HER2)-low, we investigated the clinicopathological and prognostic characteristics of the HER2-low status in early-stage triple-negative breast cancer (TNBC). METHODS: We collected the data of patients with TNBC who received treatment at our hospital and compared the pathological complete response (pCR) rate, overall survival (OS), and breast cancer-specific survival (BCSS) between the HER2-0 and HER2-low subtypes. RESULTS: A total of 1445 patients were included in the study, of which 698 patients (48.3%) showed HER2-low status. A similar pCR rate was observed between HER2-0 and HER2-low patients (34.9% vs. 37.4%; P = .549). T staging, N staging, and HER2 status were associated with BCSS, whereas T staging and N staging were associated with OS. Patients with the HER2-low status showed better BCSS than those with the HER2-0 status (96.6% vs. 93.7%; log-rank P = .027). In patients with non-pCR, the BCSS of the HER2-low subgroup was better than that of the HER2-0 subgroup (log-rank P = .047); however, no similar result was observed in patients with pCR. In patients with stage III, the BCSS and OS of the HER2-low subgroup were better than those of the HER2-0 subgroup (BCSS, log-rank P = .010; OS, log-rank P = .047). No similar results were observed in patients with stages I and II. CONCLUSION: The HER2-low expression was associated with better BCSS in TNBC, especially in the high-risk groups, suggesting that HER2-low breast cancer is a potential independent biological subtype.