RATIONALE: Radiation therapy to the brain may be effective in preventing brain metastases in patients with advanced non-small cell lung cancer. It is not yet known whether radiation therapy is more effective than observation in patients with advanced non-small cell lung cancer.

PURPOSE: This randomized phase III trial is studying radiation therapy to the brain to see how well it works compared with observation in preventing brain metastases in patients with advanced non-small cell lung cancer.

OBJECTIVES:

Primary

• Determine the effectiveness of prophylactic cranial radiotherapy in patients with advanced non-small cell lung cancer that is responsive to gefitinib or erlotinib hydrochloride.

Secondary

• Determine the progression-free survival in patients treated with this regimen.
• Determine the overall survival in patients treated with this regimen.
• Determine the safety and tolerability of this regimen in these patients.
• Determine the psycho-neurological effects of this regimen in these patients.
• Determine the quality of life of patients treated with this regimen.

OUTLINE: This is a multicenter study. Patients are stratified according to prior chemotherapy regimens (first line vs second line), and disease response status (complete response or partial response vs stable disease). Patients are randomized to 1 of 2 treatment groups.

• Group 1: Patients undergo prophylactic brain radiotherapy.
• Group 2: Patients undergo observation. Patients complete quality of life (HVLT, K-ADL, EORTC QLQ-C30, and EORTC-BN20) questionnaires periodically.

After completion of study therapy, patients are followed up periodically.

DISEASE CHARACTERISTICS:

• Histologically confirmed non-small cell lung cancer

  • Stage IIIB or IV disease
  • Must have had ≥ 8 weeks of gefitinib or erlotinib hydrochloride therapy

• At least 12 weeks of complete response or partial response since starting gefitinib or erlotinib hydrochloride

  • Stable disease allowed provided 1 of the following criteria is met:

    • EGFR mutation (exon 19 or 21)

    • Having ≥ 2 of the following 3 factors:

      • Female
      • Never smoked
      • Histologically confirmed adenocarcinoma of the lung

• No evidence of brain metastases by CT scan or MRI within the past 4 weeks

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• ANC ≥ 1,500/mm^3
• Platelet count ≥ 150,000/mm^3
• Bilirubin < 1.5 mg/dL
• Serum creatinine < 1.5 times upper limit of normal

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Received 1 or 2 prior systemic chemotherapy regimens