OBJECTIVES:~Primary~Determine the effect of stereotactic radiosurgery, temozolomide, and erlotinib hydrochloride on cognitive function in patients with non-small cell lung cancer and brain metastases.~Secondary~Determine the feasibility and safety of this regimen, in terms of tumor response, time to tumor progression in brain, survival, physical functioning, and quality of life, in these patients.~Determine the frequency of O6-methylguanine-DNA methyltransferase promoter methylation in these patients.~OUTLINE: This is a multicenter study.~Patients undergo stereotactic radiosurgery on day -7. Patients receive oral temozolomide once daily on days 1-5 and oral erlotinib hydrochloride once daily on days 1-23. Treatment with temozolomide and erlotinib hydrochloride repeats every 28 days in the absence of disease progression or unacceptable toxicity.~Patients undergo cognitive function evaluation as measured by Mini-Mental Status Exam administration and scoring; quality of life assessment as measured by Functional Assessment of Cancer Therapy subscale; and physical functioning assessment as measured by Katz index of activities of daily living and Karnofsky performance status at baseline and then every 8 weeks during study treatment.~Tumor tissue is examined by O6-methylguanine-DNA methyltransferase (MGMT gene) promotor methylation.~After completion of study therapy, patients are followed every 3 months.~PROJECTED ACCRUAL: A total of 54 patients will be accrued for this study.
RATIONALE: Treatment with radiosurgery, temozolomide, and erlotinib may affect brain function (the ability to think, learn, remember, and judge) in patients with non-small cell lung cancer and brain metastases. A study that evaluates brain function may help doctors plan the best treatment.~PURPOSE: This phase II trial is studying the effect of radiosurgery, temozolomide, and erlotinib on brain function in patients with non-small cell lung cancer and brain metastases.