Stereotactic Body Radiotherapy for Oligo-Progression Metastatic Non-Small Cell Lung Cancer

The goal of this clinical trial is to learn if Stereotactic Body Radiotherapy (SBRT) can treat the oligo-progressive metastatic non-small cell lung cancer (NSCLC) after first-line chemotherapy. The main questions it aims to answer are: Does SBRT improve progression-free survival in oligo-progressive metastatic non-small cell lung cancer after first-line chemotherapy? Does SBRT improve overall survival and quality of life in oligo-progressive metastatic non-small cell lung cancer after first-line chemotherapy? Researchers will compare SBRT in combination with standard of care (SOC) and SOC only to see if SBRT works to treat oligo-progressive metastatic non-small cell lung cancer after first-line chemotherapy. Participants will: Take SBRT in combination with SOC or SOC only. Visit the clinic for checkups and tests as required by the study. Keep a diary of their symptoms and complete the quality of life assessment questionnaire.