Primary Tumor Resection

Osimertinib is a standard first-line treatment for patients with metastatic non-small cell lung cancer harboring an epidermal growth factor receptor exon 19 deletion or exon 21 L858R mutation. Although osimertinib can provide effective disease control, most patients eventually experience disease progression, and the primary lung tumor may remain an important site of treatment resistance. This multicenter, randomized, open-label phase III trial will evaluate whether surgical removal of the primary lung tumor, in addition to continued osimertinib treatment, prolongs progression-free survival in patients with EGFR-mutated oligometastatic non-small cell lung cancer. All participants will initially receive osimertinib 80 mg orally once daily for 12 weeks. Participants who have a partial response or stable disease according to RECIST version 1.1 and remain suitable for surgery will be randomly assigned in a 1:1 ratio to continue osimertinib alone or to undergo primary lung tumor resection followed by resumption of osimertinib. The study will also evaluate overall survival, safety, pathologic response, quality of life, patterns of disease progression, and changes in molecular biomarkers.