This gene plays a critical role in controlling epithelial cell growth, differentiation,2,3 and possibly angiogenesis.4,5 Approximately 15–20% of primary invasive breast cancers are HER2 positive.6 HER2 gene amplification is associated with a relatively poor prognosis with increased risk of recurrence and metastasis,7 but is also a predictive factor for response to anthracycline-based chemotherapy and treatment benefit with anti-HER2 therapies such as trastuzumab, lapatinib, and pertuzumab.8 This evidence concerns the gene ERBB2 and invasive breast carcinoma.