Radiation Therapy in Treating Patients With Stage I Non-Small Cell Lung Cancer

OBJECTIVES: Primary * To determine the 1-year rate of ≥ grade 3 adverse events that are definitely, probably, or possibly related to treatment with single fraction vs multiple fraction stereotactic body radiotherapy in medically inoperable patients with stage I peripheral non-small cell lung cancer. Secondary * To estimate the 1-year primary tumor control rate in these patients. * To estimate the 1-year overall survival and disease-free survival rate of these patients. * To assess FDG-PET (fluorodeoxyglucose - positron emission tomography) standardized uptake value changes as a measure of treatment response and outcomes. * To determine pulmonary function changes by treatment arm and response. * To determine the association between biomarkers and primary tumor control and/or ≥ grade 2 radiation pneumonitis. OUTLINE: This is a multicenter study. Patients are stratified according to Zubrod performance status (0 vs 1 vs 2) and T stage (T1 vs T2). Patients are randomized to 1 of 2 treatment arms. After completion of study treatment, patients are followed up every 3 months for 2 years, every 6 months for 2 years, and then annually thereafter.