Abstract:Objective To investigate the clinical diagnosis and treatment of synchronous multiple primary lung cancer(SMPLC)and diagnostic value of nextgeneration sequencing( NGS ). Methods A case was initially diagnosed as “Left lung adenocarcinoma with EGFR mutation and with metastasis to the left pleura, both lungs, thoracic vertebrae”showed different therapeutic responses between primary and metastatic cancer underwent the firstline therapy with gefitinib. After puncture biopsy and NGS. It was diagnosed as simultaneous double primary lung cancer, and then given the second line therapy with gefitinib and crizotinib. Results Followedup for one month,the right lung tumor was significantly reduced, symptoms became stable. Conclusion The identification of multiple primary lung cancer (MPLC) and lung metastatic carcinoma affects the treatment and prognosis. Imaging and pathological diagnosis are sometimes indistinguishable. NGS can detect gene sequence information with high throughput and has high economic benefit ratio, which is of great significance to the individualized accurate treatment of MPLC.