SRS Study in Patients With Non-Small Cell Lung Cancer

Inclusion Criteria: 1. Cohort 1: Histologically or cytologically documented NSCLC. 2. Cohort 1: Inoperable stage IA (T1N0MO), IB (T2N0MO) and selective stage II (T3 due to chest wall involvement, N0M0). Patient refuses surgery is eligible. Secondary lung cancer is eligible if primary cancers have been cured or stable with life expectance longer than 2 years. If primary cancer is lung cancer, patient needs to be lung cancer free for more than 5 year for same histology or more than 2 years for different histology. 3. Cohort 1: Patients with hilar or mediastinal lymph nodes \<= 1cm and no abnormal hilar or mediastinal uptake on PET will be considered N0. Patients with \> 1 cm hilar or mediastinal lymph nodes on CT or abnormal PET (including suspicious but on-diagnostic uptake) may still be eligible if directed tissue biopsy of all abnormally identified areas are negative for cancer. Patient who received induction chemotherapy or other systemic therapy are eligible. 4. Cohort 1: Performance score Karnofsky performance status (KPS) 60-100. 5. Cohort 2: Histologically or cytologically documented NSCLC. 6. Cohort 2: Inoperable isolated lung parenchyma recurrent NSCLC without evidence of lymph node or mediastinal involvement (clinical stage T1-2, chest wall involvement T3, N0M0) after surgical resection or definitive radiotherapy with/without chemotherapy. Recurrent disease is defined as NSCLC with same histology, same lobe that recurs within 5 years after initial definitive therapy. Patient refuses surgery is also eligible. Patient received systemic therapy is eligible. 7. Cohort 2: Performance score KPS 60-100. 8. Cohort 3: Histologically or cytologically documented NSCLC. 9. Cohort 3: Previous history of NSCLC that has been cured or stable. New development of inoperable isolated lung parenchyma lesion that has been documented histologically or cytologically as NSCLC without evidence of lymph node or mediastinal involvement (clinical stage T1-2, chest wall involvement T3, N0M0) and not eligible for cohort 1 and recurrent disease as defined in Cohort 2. This includes NSCLC happens within 5 years after initial definitive treatment of prior NSCLC, and/or is located in the different lobes. 10. (cont.) Cohort 3: Possible stage IV disease is eligible as long as it meets the criteria above since there is no definitive way to confirm it. Patient refuses surgery is eligible. Patient received systemic therapy is eligible. 11. Cohort 3: Performance score KPS 60-100. Exclusion Criteria: 1. Any tumor involving main bronchus, major vessels, heart, esophagus, trachea, carina, spinal cord. 2. Any tumor that causes collapsed lobe of lung. 3. Any tumor with malignant pleural effusion. 4. Direct evidence of hilar, mediastinal lymph node or distant metastasis based on staging work up. 5. Pregnancy. Patients (men and women) of child bearing potential should use an effective (for them) method of birth control throughout their participation in this study.