HER2‐enriched subtype composed approximately 20% of breast cancer, and HER2 overexpression served as a strong indicator toward poor prognosis even for small‐size T1a, b breast cancer.2 The anti‐HER2 monoclonal antibody, trastuzumab, already established its role as the standard regimen for HER2+ breast cancer. This evidence concerns the gene ERBB2 and breast cancer.