RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die.

PURPOSE: Phase II trial to study the effectiveness of temozolomide in treating patients who have stage IIIB, stage IV, or recurrent non-small cell lung cancer.

OBJECTIVES: I. Determine the objective response rate to temozolomide in previously treated (closed to accrual 8/01) and chemotherapy-naive patients with advanced non-small cell lung cancer. II. Determine the freedom from progression median, and 1-year and 2-year survival rates in these patients on this regimen.

OUTLINE: Patients are stratified by prior chemotherapy (yes (closed to accrual 8/01) vs no). Patients receive oral temozolomide daily for 42 days. Treatment repeats every 8 weeks for up to 2 years in the absence of disease progression or unacceptable toxicity. Patients are followed every 2 months.

PROJECTED ACCRUAL: Up to 66 patients (33 per stratum (previously treated stratum closed to accrual 8/01)) will be accrued for this study within 2 years.

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