Surgery Versus Stereotactic Body Radiation Therapy for Stage up to IA2 (T1a or T1b) Non-small Cell Lung Cancer

Inclusion Criteria: * Patients aged 18-75 * Pathologically (histologically or cytologically) proven NSCLC. * Stage IA2 T1aN0M0 or T1bN0M0 only, fit for surgery. * Tumor ≤ 2 cm (T1a or T1b according to AJCC, 8th ed.) * Hilar or mediastinal lymph nodes ≤ 1 cm with no abnormal hilar or mediastinal uptake on PET scan are considered N0. * Patients with hilar or mediastinal lymph nodes \> 1 cm on CT scan or abnormal PET scan (including suspicious but non-diagnostic uptake) are eligible, provided directed tissue biopsies by EBUS or mediastinoscopy of all abnormally identified areas are negative for cancer. * EBUS preferable * No regional or distant metastases. * Resectable disease and treatable by SBRT * Peripherally located tumor. * Primary tumor within or touching the zone of the proximal bronchial tree, defined as a volume of 2 cm in all directions around the proximal bronchial tree are excluded (carina, right and left main bronchi, right and left upper lobe bronchi, intermedius bronchus, right middle lobe bronchus, lingular bronchus, right and left lower lobe bronchi). * No involvement of the central pleura and/or structures of the mediastinum. * Staging studies must be done within 8 weeks prior to study entry * Patients must provide study specific informed consent prior to study entry. Exclusion Criteria: * Previously operated lung cancer. * Previous thoracic irradiation. * Patients with a history of other malignancies, except: adequately treated non-melanoma skin cancer, curatively treated in-situ cancer, or other solid tumors curatively treated with no evidence of disease for ≥ 5 years following the end of treatment and which, in the opinion of the treating physician, do not have a substantial risk of recurrence of the prior malignancy. * Pulmonary nodule manifested as pure ground-glass opacity. * Severe pulmonary hypertension. * Severe cardiac, hepatic or renal insufficiency. * Severe peripheral vascular disease. * Severe cerebral or psychiatric pathologies. * Severe chronic heart disease. * Life expectancy \< 6 months. * Pregnant or lactating woman. * Unwilling to have follow-up. * Central tumor where pneumonectomy might be considered.