Radiation Therapy in Treating Patients With Non Small Cell Lung Cancer That Has Been Completely Removed by Surgery

OBJECTIVES: Primary * Compare the disease-free survival of patients with completely resected non-small cell lung cancer treated with conformal thoracic radiotherapy vs no radiotherapy. Secondary * Determine the toxicity, in particular cardiac and pulmonary toxicity, of these regimens in these patients. * Compare the local control in patients treated with these regimens. * Determine patterns of recurrence in patients treated with these regimens. * Determine the overall survival of patients treated with these regimens. * Assess second cancers in patients treated with these regimens. * Assess prognostic factors and predictive factors of treatment effect on disease-free survival and overall survival of patients treated with these regimens. * Determine the cost per recurrence-free year of life. OUTLINE: This is a multicenter, randomized study. Patients are stratified according to participating center, prior chemotherapy (neoadjuvant alone vs adjuvant vs none), number of lymph stations involved (0 vs 1 vs ≥ 2), histology (squamous cell vs other), and use of pretreatment positron emission tomography scans (yes vs no). Patients are randomized to 1 of 2 treatment arms. * Arm I: Beginning within 4-8 weeks after surgery or 2-6 weeks after chemotherapy, patients undergo adjuvant thoracic conformal radiotherapy once daily, 5 days per week, for 6 weeks. * Arm II: Patients do not undergo adjuvant thoracic radiotherapy. After completion of study therapy, patients are followed periodically for up to10 years. PROJECTED ACCRUAL: A total of 700 patients will be accrued for this study.