ERBB2 and breast cancer: Trastuzumab (Herceptin), when combined with chemotherapy, can extend the survival of patients with early stage and metastatic HER2 overexpressed (> 30% of tumor cells, 3 + by immunohistochemistry, IHC) and/or amplified (FISH HER2/CEP7 ratio > 2.2) breast cancer [4, 5].