The purpose of this study was to investigate the prognostic difference between patients with HER2-low expression and HER2-zero BC.<h4>Methods</h4>An electronic search of Pubmed, Embase, Cochrane Library, and Web of Science databases was performed to screen studies that included prognostic comparisons between HER2-zero and HER2-low expression groups. This evidence concerns the gene ERBB2 and breast cancer.