Clinically, tumors with a strong staining of HER2 in immunohistochemistry (IHC) staining (more than 10% of tumor cells positive for HER2) or gene amplification detected by fluorescence in situ hybridization (FISH) are defined as HER2 positive, following the guidelines set by the American Society of Clinical Oncology-College of American Pathologists (ASCO-CAP) [10]. The gene discussed is ERBB2; the disease is neoplasm.