Purpose

The primary purpose of this study is to determine whether breast cancer tumors respond (as measured by pathologic complete response: the absence of microscopic evidence of invasive tumor cells in the breast) to combined chemotherapy of AC(doxorubicin and cyclophosphamide) followed by paclitaxel plus trastuzumab or lapatinib or both given before surgery to patients with HER2-positive breast cancer. Trastuzumab will also be given to all patients after surgery. The study will also evaluate the toxic effects of the chemotherapy combination, including effects on the heart, and will determine survival and progression-free survival 5 years after treatment. Also, the study will look at whether there are gene expression profiles in the tumor tissue that can predict pathologic complete response.