Capecitabine in Treating Women With Advanced or Metastatic Breast Cancer

DISEASE CHARACTERISTICS: Histologically and/or cytologically confirmed breast cancer Advanced and/or metastatic disease At least 1 measurable lesion At least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan No CNS metastases Hormone receptor status: Not specified PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: Karnofsky 70-100% Life expectancy: At least 12 weeks Hematopoietic: Neutrophil count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hepatic: Bilirubin no greater than 1.25 times upper limit of normal (ULN) AST/ALT no greater than 2.5 times ULN (5 times ULN if liver metastases present) Alkaline phosphatase no greater than 2.5 times ULN (5 times ULN if liver metastases present OR 10 times ULN if bone metastases present) No hepatitis Renal: Creatinine no greater than 1.5 times ULN Creatinine clearance at least 50 mL/min Cardiovascular: No clinically significant cardiac disease No congestive heart failure No symptomatic coronary artery disease No cardiac arrhythmias poorly controlled with medication No myocardial infarction within the past 12 months even if adequately controlled with medication Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative No severe pain inadequately controlled by analgesics No prior severe and unexpected reaction to fluoropyrimidine therapy No known hypersensitivity to fluorouracil No impaired physical integrity of the upper gastrointestinal tract No malabsorption syndrome No inability to swallow tablets No history of uncontrolled seizures, central nervous system disorder, or psychiatric disability that would preclude study participation No serious uncontrolled infection PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: At least 2 but no more than 3 prior chemotherapy regimens At least 1 prior chemotherapy regimen containing paclitaxel and an anthracycline as adjuvant therapy or for advanced and/or metastatic disease Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to target lesions unless there is evidence of new disease within the irradiated field No concurrent radiotherapy Surgery: No prior organ allografts Other: At least 4 weeks since prior investigational drug No concurrent enrollment on other investigational study No other concurrent anticancer agents