ERBB2 and breast cancer: When comparing pCR rates across different molecular subtypes, it was observed that HER2-negative tumors represented a small proportion of tumors with pCR.(17) This can be partially explained by the high prevalence of HER2-positive tumors in our sample (64.4%) compared to the expected distribution of molecular subtypes in breast cancer.(18) Due to this selection bias, the assessment of the response stratified by the other molecular subtypes was limited.