Karenitecin in Treating Patients With Relapsed or Refractory Non-Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed relapsed or refractory non-small cell lung carcinoma (NSCLC) * Squamous cell carcinoma * Basaloid carcinoma * Adenocarcinoma * Bronchoalveolar carcinoma * Adenosquamous cell carcinoma * Large cell carcinoma * Large cell neuroendocrine carcinoma * Giant cell carcinoma * Sarcomatoid carcinoma * Non-small cell carcinoma not otherwise specified * Histologic or cytologic documentation of recurrence required if disease previously completely resected * Must have had only 1 prior chemotherapy regimen, including adjuvant or neoadjuvant therapy for NSCLC * At least 1 unidimensionally measurable lesion * At least 20 mm with conventional techniques OR * At least 10 mm with spiral CT scan * Lesions that are not considered measurable include the following: * Bone lesions * Leptomeningeal disease * Ascites * Pleural/pericardial effusion * Abdominal masses not confirmed and followed by imaging techniques * Cystic lesions * Tumor lesions in a previously irradiated area * Controlled CNS metastases allowed if patient is neurologically stable and off steroids PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-1 Life expectancy: * Not specified Hematopoietic: * Granulocyte count at least 1,500/mm3 * Platelet count at least 100,000/mm3 Hepatic: * Bilirubin no greater than 1.5 mg/dL Renal: * Creatinine no greater than upper limit of normal Other: * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * Not specified Chemotherapy: * See Disease Characteristics * At least 4 weeks since prior chemotherapy (6 weeks for mitomycin) * No prior irinotecan or other camptothecin drug * No other concurrent chemotherapy Endocrine therapy: * See Disease Characteristics * No concurrent hormonal therapy except for non-cancer-related conditions (e.g., insulin for diabetes) * No concurrent steroids except for adrenal failure Radiotherapy: * See Disease Characteristics * Prior radiotherapy for symptomatic lesions or those that might produce disability (e.g., painful bone metastases) allowed if other measurable disease present * At least 4 weeks since prior radiotherapy * No concurrent palliative radiotherapy Surgery: * See Disease Characteristics