PRIOR CONCURRENT THERAPY: Biologic therapy: At least 2 weeks since prior immunotherapy and recovered No concurrent filgrastim (G-CSF) with nitrocamptothecin No concurrent anticancer immunotherapy Chemotherapy: See Disease Characteristics At least 2 weeks since prior chemotherapy and recovered No other concurrent anticancer chemotherapy Endocrine therapy: No concurrent anticancer hormonal therapy Radiotherapy: At least 2 weeks since prior radiotherapy and recovered No concurrent anticancer radiotherapy Surgery: At least 2 weeks since prior surgery and recovered No planned major surgery within 8 weeks after initiation of treatment