ctDNA-Guided CURB for OPD mNSCLC on TKI (CURB-TKI)

Inclusion Criteria: 1. Age 18 or older. 2. Able to do most daily activities (ECOG 0-2). 3. Able and willing to sign an informed consent form to join the study. 4. Metastatic disease detected on imaging and histologically confirmed NSCLC on first-line TKI therapy 5. Willing to give a blood sample for ctDNA analysis. 6. No upper limit to the number of total metastatic sites, but a maximum of five progressive metastatic sites, inclusive of primary disease and metastatic lesions, all of which must be extracranial 7. Prior radiation therapy near progressive lesions is allowed if applicable. 8. All sites of oligoprogression that can be safely treated with SBRT or hypofractionated ablative radiotherapy 9. Oligoprogressive disease is evaluated independently for each lesion using specific criteria. 10. Stable brain metastases allowed if asymptomatic and do not require corticosteroids. 11. Oligoprogressive lesions previously treated with external beam radiation are eligible as long they are clinically asymptomatic, and re-treatment is possible according to the investigator. Prior conventional, non-stereotactic radiotherapy for palliative -purposes is allowed, and if the palliated lesion subsequently progressed but remains asymptomatic and does not require immediate radiotherapy, the lesion can still be counted toward one of the five oligoprogressive lesions 12. Participant is able (i.e. sufficiently fluent or with the assistance of a translator) and willing to complete the quality of life and/or health utility questionnaires in English 13. Accessible for treatment and follow-up. Exclusion Criteria: 1. More than 5 extracranial sites of progressive disease. 2. Pregnant. 3. Leptomeningeal disease. 4. Serious health issues that prevent radiotherapy, like ataxia-telangiectasia or scleroderma. 5. Prior radiation therapy near the progressive lesion that would prevent treatment with SBRT due to exceeding limits of healthy tissue tolerance. 6. Any other condition that the investigator believes makes participation in the study inappropriate.