ERBB2 and breast cancer: In our study, we found that among HR-negative BC patients, the pCR rate of HER2-low patients was significantly lower than that of HER2-zero patients (23.2% vs 38.9%, p = 0.004), and the results of the unifactorial and multifactorial analyses of the influence of NAC on the pCR rate of HER2-low HR-negative BC suggested that the clinical T-stage was an independent influencing factor.