Temozolomide in Treating Patients With Stage IIIB, Stage IV, or Recurrent Non-small Cell Lung Cancer

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 PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil 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 2.0 mg/dL Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after study No other active invasive malignancies PRIOR CONCURRENT THERAPY: Biologic therapy: Prior biologic therapy allowed Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics Recovered from prior radiotherapy Surgery: See Disease Characteristics