RATIONALE: Drugs used in chemotherapy, such as epirubicin, cyclophosphamide, docetaxel, and capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. Monoclonal antibodies, such as trastuzumab, can block tumor growth in different ways. Some find tumor cells and kill them or carry tumor-killing substances to them. Others interfere with the ability of tumor cells to grow and spread. Giving combination chemotherapy together with monoclonal antibodies before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed. Giving monoclonal antibodies after surgery may kill any tumor cells that remain after surgery. It is not yet known whether combination chemotherapy is more effective with or without capecitabine and/or trastuzumab in treating breast cancer.