Radiation Therapy and Stereotactic Radiosurgery With or Without Temozolomide or Erlotinib in Treating Patients With Brain Metastases Secondary to Non-Small Cell Lung Cancer

Inclusion Criteria: Histologically confirmed non-small cell lung cancer One to 3 intraparenchymal brain metastases by contrast-enhanced MRI, meeting the following criteria: Well circumscribed tumor(s) Maximum diameter ≤ 4.0 cm If multiple lesions are present and one lesion is at the maximum diameter, the other lesions must not exceed 3.0 cm in maximum diameter No metastases within 10 mm of the optic apparatus such that a portion of the optic nerve or chiasm would be included in the high-dose stereotactic radiosurgery boost field No metastases in the brainstem, midbrain, pons, or medulla No prior complete resection of all known brain metastases Subtotal resection allowed provided residual disease is ≤ 4.0 cm in maximum diameter No clinical or radiographic evidence of progression (other than study lesion[s]) within the past month Patients with brain metastases at initial presentation do not require 1 month of scans documenting stable disease Stable extracranial metastases allowed No known or pre-existing liver metastases No leptomeningeal metastases by MRI or cerebrospinal fluid evaluation Synchronous brain metastases at initial diagnosis allowed Performance status - Zubrod 0-1 Hemoglobin ≥ 8 g/dL Absolute neutrophil count ≥ 1,000/mm^3 Platelet count ≥ 100,000/mm^3 AST < 2 times upper limit of normal (ULN) Alkaline phosphatase < 2 times ULN unless due to elevated bone metastases Total bilirubin normal Lactic dehydrogenase < 2 times ULN Creatinine < 1.5 times ULN No clinically active interstitial lung disease Chronic stable asymptomatic radiographic changes allowed Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative Neurologic function status 0-2 No other major medical illness or psychiatric impairment that would preclude study participation No history of allergic reaction attributed to compounds of similar chemical or biologic composition to erlotinib or temozolomide No concurrent immunotherapy No concurrent biologic therapy, excluding growth factors and epoetin alfa No prior temozolomide or erlotinib No other concurrent chemotherapy during study radiotherapy Other concurrent chemotherapy allowed after study radiotherapy, except for the following: Temozolomide or erlotinib (arm I only) Erlotinib (arm II only) Temozolomide (arm III only) No prior cranial radiotherapy No concurrent intensity-modulated radiotherapy Concurrent radiotherapy to painful bone lesions allowed No concurrent radiotherapy to more than 15% of bone marrow No other concurrent therapy for brain metastases unless a recurrence is detected More than 30 days since prior investigational drugs No concurrent enzyme-inducing antiepileptic drugs including, but not limited to, any of the following (for patients randomized to receive erlotinib): Phenytoin Carbamazepine Rifampin Phenobarbital Primidone Oxcarbazepine No other concurrent investigational drugs No concurrent Hypericum perforatum (St. John's wort) No drugs that alter gastric pH (e.g., proton pump inhibitors or H2 antagonists) within 4 hours after erlotinib administration (arm III patients only)