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