PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Must have previously received 1 but no more than 2 chemotherapy regimens At least 1 prior regimen administered for metastatic disease At least 1 prior regimen containing an anthracycline or paclitaxel At least 4 weeks since prior chemotherapy Endocrine therapy: Not specified Radiotherapy: At least 3 weeks since prior radiotherapy No prior strontium 89 radiotherapy Prior radiotherapy must have been to less than 25% of bone marrow Surgery: At least 4 weeks since any major surgery