PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No prior irinotecan, topotecan, or other camptothecin analogues At least 3 weeks since prior chemotherapy Endocrine therapy: No concurrent corticosteroids to control CNS disease Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy Surgery: At least 4 weeks since prior major surgery