Patients receive CMF comprising cyclophosphamide orally on days 1-14 or IV on days 1 and 8 and methotrexate IV and fluorouracil IV on days 1 and 8. Patients also receive trastuzumab (Herceptin®) IV over 30-90 minutes once weekly beginning on day 1. Treatment repeats every 4 weeks for 8 courses. Patients then receive trastuzumab once every 3 weeks in the absence of disease progression, unacceptable toxicity, or patient refusal.