The addition of trastuzumab to preoperative chemotherapy for HER2-positive (HER2+) breast cancer has been tested in several schedules and combinations and has led to improved pathologic complete response (pCR) rates, which seem to correlate with improved outcomes and clinical benefit [2, 3] and has become a standard of care for HER2-positive breast cancers. This evidence concerns the gene ERBB2 and breast cancer.