RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining more than one chemotherapy drug may kill more tumor cells.

PURPOSE: Phase II trial to study the effectiveness of combining docetaxel and carboplatin in treating women who have metastatic breast cancer.

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.

OUTLINE: This is a multicenter study. Patients receive docetaxel IV over 1 hour and carboplatin IV over 30 minutes on day 1. Treatment repeats every 3 weeks in the absence of disease progression or unacceptable toxicity. Patients who achieve stable disease (SD), partial response (PR), or complete response (CR) may receive 4 additional courses past SD, PR, or CR. Patients are followed every 6 months for 2 years and then annually for 3 years.

DISEASE CHARACTERISTICS: Histologically proven metastatic adenocarcinoma of the breast Measurable disease At least 20 mm in at least 1 dimension Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: Granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than upper limit of normal (ULN) SGOT/SGPT no greater than 2.5 times ULN Alkaline phosphatase no greater than ULN OR SGOT/SGPT no greater than ULN Alkaline phosphatase no greater than 4 times ULN Renal: Creatinine no greater than 1.5 times ULN Cardiovascular: No myocardial infarction within the past 6 months No congestive heart failure No unstable angina No clinically significant pericardial effusion or arrhythmia Other: No other invasive malignancy within the past 5 years except curatively treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix No active unresolved infection No prior hypersensitivity reaction to docetaxel No grade 2 or greater sensory or motor neuropathy Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent prophylactic filgrastim (G-CSF) during the first course of study therapy Chemotherapy: No prior chemotherapy for metastatic disease Prior adjuvant chemotherapy allowed More than 1 year since prior paclitaxel, docetaxel, cisplatin, or carboplatin No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy to breast, chest wall, or axilla No prior radiotherapy to greater than 30% of bone marrow No concurrent radiotherapy Surgery: At least 4 weeks since prior major surgery and recovered Other: More than 7 days since prior IV antibiotics No concurrent experimental drugs