DISEASE CHARACTERISTICS: Histologically or cytologically confirmed non-small cell lung cancer (NSCLC) Reconfirmation of NSCLC required only if complete response for greater than 1 year Measurable or evaluable disease Tumor shrinkage or stability for at least 4 weeks on initial chemotherapy CNS metastases allowed, if symptoms controlled for greater than 8 weeks after surgery or radiotherapy

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: 0-1 Life expectancy: At least 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin normal AST no greater than 2 times upper limit of normal (ULN) Renal: Creatinine no greater than 2.5 times ULN Cardiovascular: No New York Heart Association class III or IV heart disease Other: No active infection At least 5 years since any other prior malignancy except curatively treated basal or squamous cell skin cancer, carcinoma in situ, or other cancers No grade 2 or worse peripheral neuropathy No uncontrolled diabetes mellitus No other serious underlying disease Not pregnant or nursing Fertile patients must use effective contraception

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