RecruitingPhase 2Radiation therapyLocal Ablative Therapy to Oligoresidual Metastasis in EGFR Mutated Non-small Cell Lung CancerThis is an open-label, multicentre, randomized phase II clinical trial. Patients with stage IV (AJCC 9th edition) non-small cell lung cancer (NSCLC) harboring EGFR exon 19 deletion or exon 21 L858R mutation, who had less than or equal to 3 active oligoresidual cancer sites amenable to local ablative therapy (LAT) (as determined by physician) after 3-6 months of firstline osimertinib treatment, are eligible. Subjects will be randomized 1:1 to osimertinib with or without LAT.