Importantly, approaches to breast cancer treatment have evolved over the past several decades with the widespread uptake of adjuvant hormone therapy, including tamoxifen in the 1990s and aromatase inhibitors in the mid-2000s, advances in chemotherapy regimens including a shift towards taxane-containing drugs [5–7], and the introduction of trastuzumab to treat early-stage human epidermal growth factor receptor 2 (HER2)-positive tumors in 2005 [8, 9]. This evidence concerns the gene ERBB2 and breast cancer.