PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics No greater than 1 prior NSCLC chemotherapy regimen, excluding low dose cisplatin as a radiosensitizer No prior irinotecan or docetaxel At least 4 weeks since prior chemotherapy Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy No prior radiotherapy to greater than 25% of bone marrow Surgery: See Disease Characteristics Other: No concurrent phenytoin, phenobarbital, or other anticonvulsants