WBRT & Erlotinib in Advanced NSCLC and Brain Metastases

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed advanced non-small cell lung cancer (NSCLC) meeting 1 of the following criteria: * Newly diagnosed multiple brain metastases not suitable for first-line chemotherapy * Relapsed NSCLC with newly diagnosed multiple brain metastases * Relapsed after second-line chemotherapy with newly diagnosed multiple brain metastases NOTE: \*Biopsy of brain metastases is not required * Diagnosis of brain metastases must be confirmed by contrast CT scan or MRI within the past 4 weeks * Symptoms attributable to brain metastases * Patients who have undergone craniotomy with incomplete resection are eligible * Clinician certain that whole-brain radiotherapy (WBRT) will be beneficial * No evidence of solitary brain metastasis on MRI that can be treated with surgical resection, radiosurgery, or stereotactic radiotherapy * No more than 3 sites (organ systems) of extracranial metastases * No liver metastases PATIENT CHARACTERISTICS: * Karnofsky performance status 70-100% * RTOG recursive partitioning analysis (RPA) class I or II * Serum bilirubin \< 2 times upper limit of normal (ULN) * AST and ALT \< 2 times ULN (\< 5 times ULN if liver metastases are present) * Creatinine \< 5 times ULN * Able to take oral medication * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Caretaker able and willing to participate in the study * Patient and caretaker have access to a telephone and willing to respond to telephone interview * No other prior or concurrent malignant disease likely to interfere with study treatment or comparisons * No evidence of other significant laboratory finding or concurrent uncontrolled medical illness, that in the opinion of the investigator, would interfere with study treatment or results comparison or render the patient at high risk for treatment complications including, but not limited to, any of the following: * Severe uncontrolled infection * Unstable angina * Myocardial infarction within the past month * Uncontrolled inflammatory bowel disease (e.g., Crohn's disease or ulcerative colitis) * Acute renal failure PRIOR CONCURRENT THERAPY: * See Disease Characteristics * At least 28 days since prior chemotherapy (for relapsed patients originally treated with chemotherapy) * No prior cranial radiotherapy * No prior anti-cancer EGFR therapy (e.g., erlotinib, gefitinib, or cetuximab) * No prior treatment for brain metastases (e.g., radiosurgery, radiotherapy, or chemotherapy) * Prior radiotherapy to the primary tumor and/or systemic treatment to metastatic sites of disease allowed * No concurrent cyclooxygenase-2 (COX-2) inhibitors