OBJECTIVES: I. Determine the safety and toxicity of preoperative trastuzumab (Herceptin) and paclitaxel followed by postoperative doxorubicin and cyclophosphamide in women with locally advanced breast cancer with HER2 overexpression. II. Determine tumor response in these patients treated with this regimen. III. Assess the effect of this regimen on tumor histology and the potential molecular determinants of response in these patients.