PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior immunotherapy (e.g., interferon, monoclonal antibodies) No concurrent interleukin-11 for treatment or prevention of thrombocytopenia No concurrent prophylactic colony stimulating factors Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for melphalan, carmustine, or mitomycin) At least 72 hours since prior hydroxyurea No prior 506U78 No other concurrent chemotherapy Endocrine therapy: At least 72 hours since prior glucocorticoids Concurrent continuation of steroids for adrenal failure allowed No concurrent hormones except for nondisease related conditions (e.g., insulin for diabetes) No concurrent dexamethasone or other steroidal antiemetics Radiotherapy: At least 4 weeks since prior radiotherapy No concurrent palliative radiotherapy No concurrent whole brain irradiation for documented CNS disease Surgery: Not specified Other: At least 72 hours since prior aspirin