HER2-positive breast cancer represents 15–20% of breast cancer cases [18,19] and is defined by the overexpression of HER2 protein as characterized by immunohistochemistry (IHC) status or by florescence or chromogenic in situ hybridization (FISH/CISH) of HER2 gene copy number or a HER2/CEP17 ratio of 2 or greater [20]. The gene discussed is ERBB2; the disease is breast carcinoma.