Because nearly 45.9% of HER2-positive patients received trastuzumab-containing therapy, and the other 54.1% of HER2-positive were treated in the absence of trastuzumab, we evaluated the DSS, DFS, and OS outcomes of breast cancer patients stratified by HER2 status in the presence or absence of trastuzumab treatment. Here, ERBB2 is linked to breast cancer.