DISEASE CHARACTERISTICS: Histologically confirmed metastatic breast cancer No CNS metastases No rapidly progressing visceral disease Previously irradiated lesions(s) may be designated as measurable indicator tumor(s) only if more than 6 months since radiotherapy, patient has no other measurable disease regrowth, and bidimensionally measurable regrowth is documented within 2 months prior to study Stratum 1 (hormonal): Must be hormone receptor positive (ER or PR) Prior hormonal therapy only allowed for metastatic disease Must have progressed on last hormonal regimen Must have at least one bidimensionally measurable tumor Stratum 2 (chemotherapy): Hormone receptor positive or negative Must have progressed on or after prior chemotherapy (1-2 regimens) for metastatic disease (bone marrow transplant counts as 2 regimens) Prior hormonal therapy allowed Must have at least one bidimensionally measurable tumor Stratum 3 (tamoxifen): Must be hormone receptor positive (ER or PR) and progressing on tamoxifen No symptomatic visceral metastasis if on adjuvant tamoxifen at time of systemic recurrence Must have at least one bidimensionally measurable tumor, or lytic bone lesion which measures at least one cm in diameter Hormone receptor status: See above