(a) Comparison between TCGA Her2-negative BC (n = 985) and TCGA Her2-positive BC (n = 120); (b) comparison between TCGA Her2-positive BC (n = 120) and this study Her2-positive trastuzumab-resistant MBC cohort (n = 22); (c) comparison between this study Her2-positive trastuzumab-resistant MBC cohort (n = 22) and all TCGA BC (n = 1105). This evidence concerns the gene ERBB2 and breast cancer.