PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy No concurrent immunotherapy No concurrent immunomodulating agents Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) No other concurrent cytostatic or cytotoxic chemotherapy Endocrine therapy: See Disease Characteristics No concurrent hormonal therapy No concurrent dexamethasone Radiotherapy: At least 3 weeks since prior radiotherapy No prior radiotherapy to more than 25% of bone marrow No concurrent radiotherapy Surgery: At least 3 weeks since prior major surgery