Radiation Therapy Combined With Either Gefitinib or Temozolomide in Pats With NSCLC and Brain Metastases

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed non-small cell lung cancer AND newly diagnosed brain metastases meeting 1 of the following criteria: * Multiple brain metastases * Single brain metastasis not amenable to potentially curative treatment * No advanced extracranial disease severely compromising vital functions and performance PATIENT CHARACTERISTICS: Age * 18 and over Performance status * WHO 0-2 Life expectancy * Not specified Hematopoietic * Hemoglobin \> 10 g/dL * Absolute neutrophil count \> 1,500/mm\^3 * Platelet count \> 100,000/mm\^3 Hepatic * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * AST and ALT ≤ 2.5 times ULN * Alkaline phosphatase ≤ 2.5 times ULN (5 times ULN in the presence of documented bone metastases) * No unstable or uncompensated hepatic disease that would preclude study participation Renal * Creatinine clearance ≥ 40 mL/min * No unstable or uncompensated renal disease that would preclude study participation Cardiovascular * No myocardial infarction within the past 3 months * No unstable or uncompensated cardiac disease that would preclude study participation Pulmonary * No clinically active interstitial lung disease * Patients with chronic stable radiographic changes who are asymptomatic eligible * No other unstable or uncompensated respiratory disease that would preclude study participation Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 12 months after completion of study treatment * No nausea, vomiting, inability to swallow whole tablets/capsules, or malabsorption syndrome that would preclude oral medication ingestion or absorption * No psychiatric disorder that would preclude giving informed consent or study compliance * No active infection * No uncontrolled diabetes mellitus * No other medical condition that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * No prior temozolomide Endocrine therapy * Concurrent corticosteroids allowed provided dose has been stable or decreasing for ≥ 4 days before study entry Radiotherapy * No prior brain irradiation Surgery * Not specified Other * No prior gefitinib or erlotinib * More than 30 days since prior investigational clinical trial participation * No other concurrent experimental drugs * No other concurrent anticancer therapy * No concurrent treatment with any of the following: * Phenytoin * Carbamazepine * Rifampin * Barbiturates * Hypericum perforatum (St. John's wort) * Other enzyme-inducing anti-epileptic drugs or tuberculostatic treatments * Any drug that contraindicates administration with study drugs