DISEASE CHARACTERISTICS: Stage IIIB, IV, or recurrent non-small cell lung cancer for which no curative therapy with surgery, radiation, or combination chemoradiotherapy exists Chemotherapy-naive patients: No prior chemotherapy OR At least 6 months since prior adjuvant, induction, or radiosensitizing chemotherapy OR Previously treated patients (closed to accrual 8/01): No more than one prior chemotherapy regimen for relapsed or metastatic disease AND/OR No more than one prior adjuvant, induction, or radiosensitizing chemotherapy within the past 6 months Measurable or evaluable disease CNS metastases allowed (previously treated metastases cannot be only site of measurable disease) No brain metastases with prior whole body irradiation