Development of HER2-targeted therapies using monoclonal antibodies (e.g., pertuzumab and trastuzumab) and tyrosine kinase inhibitors (including tucatinib, which has been found to be superior to the previously used lapatinib) over the last decade has led to significant improvement in the survival of patients with known HER2-positive breast cancer. This evidence concerns the gene ERBB2 and breast carcinoma.