Trastuzumab and Erlotinib as First-Line Therapy in Treating Women With Metastatic Breast Cancer Associated With HER2/Neu Overexpression

RATIONALE: Monoclonal antibodies such as trastuzumab can locate tumor cells and either kill them or deliver tumor-killing substances to them without harming normal cells. Biological therapies such as erlotinib may interfere with the growth of tumor cells and slow the growth of the tumor. Combining trastuzumab with erlotinib may kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of combining trastuzumab with erlotinib as first-line therapy in treating women who have metastatic breast cancer associated with HER2/neu overexpression.