Standard Maintenance Therapy (SMT) vs Local Consolidative Radiation Therapy and SMT in OM-NSCLC

Inclusion Criteria: 1. Age \> 18 years 2. Patients with ECOG performance status of 0-2 3. Patients with pathologically proven diagnosis of NSCLC 4. Patients with 1-5 sites of metastatic disease not including the primary tumor and regional nodes (less than or equal to 3 metastatic lesions in one organ will be eligible and 4 or more metastatic lesions in one organ will be ineligible) 5. Patients who have received standard duration of systemic therapy (4 - 6 cycles) without progression of the disease 6. Patients suitable for definitive therapy to the primary disease 7. All the Oligometastases lesions should be radiologically visible and suitable for ablative doses of radiation in accordance with the dose fractionation regimens specified in the protocol. 8. Patients who have received ablative radiation therapy or surgery or RFA for metastatic sites at presentation or during systemic therapy will be eligible provided the total number of oligometastatic sites at the time of study entry (treated site included) is less than or equal to five. 9. Patients who have received palliative RT for symptomatic bony metastases or RFA will also be eligible provided the treated site is under control on imaging. If not controlled, could be eligible for study if further ablative doses of radiation can be delivered according to the treating physician. 10. Patients who underwent surgical decompression, or stabilization followed by palliative radiation therapy for bony metastases will be eligible in the study provided the treated site is under control on imaging and patient has less than 5 sites of metastases at the time of study entry. 11. Adequate end organ function CBC/differential obtained within 15 days prior to registration on study, with adequate bone marrow function defined as follows: * Absolute neutrophil count (ANC) ≥ 500 cells/mm3; * Platelets ≥ 50,000 cells/mm3; * Hemoglobin ≥ 8.0 g/dl (Use of transfusion or other intervention to achieve Hgb ≥ 8.0 g/dl is acceptable); 12. For females of child-bearing potential, negative serum or urine pregnancy test within 14 days prior to study registration; 13. Patients willing for written informed consent and must be willing to comply with the specified follow up schedule Exclusion Criteria: 1. Patients with progressive disease after initial standard systemic therapy 2. Patients with oncogene driver mutations 3. Patients with more than 5 sites of oligo metastases 4. Patients with metastatic lesion size of more than 5 cm 5. Patients with more than three metastatic lesion in one organ 6. Patients not suitable for definitive radiation therapy to primary disease 7. Patients not suitable for ablative radiation therapy to metastatic sites 8. Patients with malignant peritoneal disease 9. Patients with malignant pleural effusion 10. Leptomeningeal disease 11. Brain metastases in the brain stem 12. Clinical or radiological evidence of spinal cord compression or metastases within 2 mm of spinal cord on MRI 13. Severe, active co-morbidity defined as follows: * Unstable angina and/or congestive heart failure requiring hospitalization within the last 6 months; * Transmural myocardial infarction within the last 6 months; * Chronic Obstructive Pulmonary Disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy at the time of registration; 14. Patients with prior history of radiation therapy to thorax 15. Patients with previous history of malignancy within last 3 years from the date of diagnosis 16. Pregnancy