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

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed stage I (T1-2, N0) non-small cell lung cancer (NSCLC) * Squamous cell carcinoma * Basaloid carcinoma * Adenocarcinoma * Bronchoalveolar carcinoma * Adenosquamous carcinoma * Large cell carcinoma * Large cell neuroendocrine carcinoma * Giant cell carcinoma * Sarcomatoid carcinoma * Non-small cell carcinoma not otherwise specified * Tridimensionally measurable solitary parenchymal lung lesion no greater than 4 cm in diameter by chest CT scan (lung windows) * No metastatic disease or hilar or mediastinal lymphadenopathy * Must have mediastinoscopy\* (anterior, cervical, or both) if mediastinal lymph nodes are greater than 1.0 cm in diameter by chest CT scan * No positive lymph nodes on mediastinoscopy\* NOTE: \*Patients may have positron-emission tomography in lieu of mediastinoscopy provided there is no fludeoxyglucose F 18 uptake in the mediastinum and hilum * Poor surgical risk, as defined by 1 of the following: * High risk due to nonpulmonary reasons, such as renal failure, cardiac failure, or hepatic dysfunction and deemed by thoracic surgeon to be unsuitable for lobectomy * Pulmonary dysfunction indicated by one or more of the following: * FEV\_1 less than 40% of predicted * DLCO less than 50% of predicted * Oxygen dependent * Chronic PaCO\_2 greater than 45 mm Hg * VO\_2 less than 15 mL/kg/min PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * 0-2 Other: * Not pregnant or nursing * Fertile patients must use effective contraception * No weight loss of more than 10% within the past 6 months * No other active (less than 30% risk of relapse after completion of prior therapy) malignancy except nonmelanoma skin cancer Chemotherapy: * No prior chemotherapy for NSCLC Radiotherapy: * No prior chest radiotherapy