OBJECTIVES: I. Determine the anti-tumor activity of docetaxel and carboplatin in women with metastatic adenocarcinoma of the breast. II. Determine the objective response rate, time to progression, and survival in patients treated with this regimen. III. Determine the toxic effects of this regimen in these patients. IV. Assess the common functional polymorphisms in genes involved in chemotherapeutic response to improve prediction of clinical outcomes and provide insight into the potential for genotype-specific drug dosage.