This study included the largest sample size thus far to explore the different clinicopathological characteristics, pathological complete responses (pCRs), and prognoses of HER2-low cancers compared with those of HER2-0 and HER2-high cancers.<h4>Methods</h4>This study included 14,642 female breast cancer patients and 544 female patients with breast cancer from the TCGA. This evidence concerns the gene ERBB2 and cancer.