Stereotactic Body Radiation Therapy in Treating Patients With Inoperable Stage I or Stage II Non-Small Cell Lung Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed non-small cell lung cancer (NSCLC) The following primary cancer subtypes are eligible: Squamous cell carcinoma Adenocarcinoma Large cell carcinoma Bronchoalveolar cell carcinoma Non-small cell carcinoma not otherwise specified Stage I or II disease based on 1 of the following tumor node metastasis (TNM) stage criteria: T1, N0, M0 T2 (≤ 5 cm), N0, M0 T3 (≤ 5 cm), N0, M0 (chest wall primary tumors only) No primary tumor of any T-stage within or touching the zone of the proximal bronchial tree* NOTE: *Defined as a volume 2 cm in all directions around the proximal bronchial tree (carina, right and left main bronchi, right and left upper lobe bronchi, intermedius bronchus, right middle lobe bronchus, lingular bronchus, and right and left lower lobe bronchi) No primary T3 tumors involving the central chest (≤ 2 cm toward carina invasion) or structures of the mediastinum Any hilar or mediastinal lymph nodes > 1 cm on CT scan OR demonstrating suspicious uptake on positron-emission tomography scan must be biopsied and confirmed negative for NSCLC The primary tumor must be deemed technically resectable with a reasonable possibility of obtaining a gross total resection with negative margins (defined as a potentially curative resection (PCR)) Deemed medically inoperable based on pulmonary function for surgical resection of NSCLC secondary to an underlying physiological problem, including any of the following medical conditions*: Baseline forced expiratory volume (FEV)_1< 40% of predicted Postoperative predicted FEV_1 < 30% of predicted Severely reduced diffusion capacity Baseline hypoxemia and/or hypercapnia Exercise oxygen consumption < 50% of predicted Severe pulmonary hypertension Diabetes mellitus with severe end organ damage Severe cerebral, cardiac, or peripheral vascular disease Severe chronic heart disease NOTE: *Patients who refuse a PCR due to preference, ideology, emotional or psychological issues, mental illness, or inability to give informed consent are not eligible No evidence of regional or distant metastases PATIENT CHARACTERISTICS: Age 18 and over Performance status Zubrod 0-2 Life expectancy Not specified Hematopoietic Not specified Hepatic Not specified Renal Not specified Cardiovascular See Disease Characteristics No active pericardial infection Pulmonary See Disease Characteristics No active pulmonary infection Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No active systemic infection No other concurrent illness that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent biologic therapy No concurrent vaccine therapy Chemotherapy No concurrent chemotherapy Endocrine therapy Not specified Radiotherapy No prior lung or mediastinal radiotherapy No concurrent standard fractionated radiotherapy No concurrent intensity modulated radiotherapy No concurrent cobalt-60 or charged particle beams (including electrons, protons, or heavier ions) Surgery See Disease Characteristics No concurrent surgery Other No other concurrent antineoplastic therapy