To ensure comparability to the stratification of the cancers included in the MSKCC and TCGA cohorts, the breast cancer cases in our cohort were mainly grouped into the HR+/HER2− (combining luminal A and luminal B/HER2−), HR+/HER2+, HR−/HER2+, and triple-negative subtypes according to the immunohistochemical staining results. This evidence concerns the gene ERBB2 and breast cancer.