Patients 18 years of age and older with previously untreated metastatic breast cancer may be eligible for this study. Newly diagnosed patients may not have received prior chemotherapy. Patients previously diagnosed with local disease may have received chemotherapy or radiation therapy at least 18 months before entering the current study. Patients may have received hormonal therapy for stage IV disease. Candidates are screened with a medical history and physical examination, blood and urine tests, x-rays, heart and lung tests, and a test to determine the presence of CEA on their tumor cells.