DISEASE CHARACTERISTICS:

• Histologically confirmed metastatic breast cancer

• Bidimensionally measurable disease

  • No bone scan abnormalities alone
  • Lytic lesions in conjunction with bone scan abnormalities allowed
  • No pure blastic bone metastases
  • No pleural or peritoneal effusions
  • No previously irradiated lesions
• Must have received 2-4 prior chemotherapy regimens, including paclitaxel and doxorubicin, for breast cancer

• Brain metastases allowed if other measurable disease exists

  • No uncontrolled or life threatening brain lesions
• No carcinomatous meningitis

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Sex:

• Female

Menopausal status:

• Not specified

Performance status:

• Karnofsky 60-100%

Life expectancy:

• Not specified

Hematopoietic:

• Granulocyte count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• AST/ALT no greater than 5 times upper limit of normal

Renal:

• Calcium no greater than 11.0 mg/dL

Other:

• Not pregnant
• Negative pregnancy test
• No history of other malignancy except carcinoma in situ of the cervix or curatively treated nonmelanoma skin cancer
• No other serious medical illnesses, including severe infection and severe malnutrition

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• See Disease Characteristics
• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas and mitomycin) and recovered
• No other concurrent chemotherapy

Endocrine therapy:

• Prior hormonal therapies for stage IV disease and/or adjuvant therapy allowed
• At least 3 weeks since prior hormonal therapy

Radiotherapy:

• See Disease Characteristics
• No prior radiotherapy to greater than 30% of the marrow bearing bone
• At least 4 weeks since prior radiotherapy and recovered
• No concurrent radiotherapy to the only measurable lesion

Surgery:

• Recovered from prior surgery
• No concurrent surgery to the only measurable lesion

Other:

• No concurrent nonprotocol treatment