The American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) have introduced guidelines for HER2 status assessments based on the level of HER2 protein overexpression determined by immunohistochemistry (IHC) and on the level of HER2 gene amplification determined by in situ hybridization (ISH) on formalin-fixed, paraffin-embedded (FFPE) breast cancer tissue sections [2]. The gene discussed is ERBB2; the disease is breast carcinoma.