Radiotherapy to Block Oligoprogression In Metastatic Non-Small-Cell Lung Cancer

Inclusion Criteria: * Metastatic disease (stage IV) detected on imaging and histologically and/or cytologically confirmed NSCLC as per the WHO Classification of Tumors and AJCC 8th Edition TNM Classification, without a driver mutation with an actionable first-line targeted therapy, for whom either ICI alone or combination ICI + chemotherapy is indicated * Oligoprogression on first-line ICI +/- chemotherapy systemic therapy after at least 3 cycles. * All sites of oligoprogression can be safely treated with SBRT or ablative radiotherapy as determined by radiation treatment preplan, including availability and tolerability of necessary technologies (e.g., active breathing control, MRLinac, fiducial insertion, etc.) and accounting for previous radiotherapy overlap. Safety must be assessed and determined by a radiation oncologist. * Patients with treated CNS disease who have radiologic and clinical evidence of stable brain metastases, with no evidence of cavitation or hemorrhage in the brain lesion, are eligible providing that they are asymptomatic and do not require corticosteroids (must have discontinued steroids at least 1 week prior to randomization). * Candidate for regulatory approved SOC first-line orsecond-line systemic therapy options. * Participants must be ≥ 18 years of age. * ECOG performance status of 0, 1 or 2. * Participants that received prior adjuvant/neoadjuvant/consolidation systemic therapy (including chemotherapy and ICI ) are eligible if at least 6 months hav…