PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy At least 4 weeks since prior biologic therapy No concurrent immunotherapy Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks since nitrosoureas or mitomycin) and recovered No greater than 3 prior chemotherapy regimens for metastatic disease No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior pelvic radiotherapy At least 4 weeks since other prior radiotherapy No prior radiotherapy to greater than 25% of bone marrow No concurrent radiotherapy Surgery: Not specified Other: No concurrent antiretroviral therapy for HIV positive patients