Primary Tumor Resection for M1a Stage Lung Cancer

Inclusion Criteria: 1. Volunteer to participate in clinical research, willing to follow and able to complete all trial procedures; 2. Aged 18-80 years (including critical values) when signing the informed consent form; 3. ECOG score 0 or 1; 4. No previous lung cancer surgery; 5. Intraoperative or postoperative pathological confirmation of M1a stage lung cancer; 6. Occult pleural metastasis found during surgery; 7. Preoperative lymph node staging is cN0; 8. First-time treatment and no radiotherapy or chemotherapy. Exclusion Criteria: 1. The lesion cannot be completely removed surgically; 2. Cytological or histological pathology confirms other lung malignancies other than lung cancer; 3. Patients who have undergone lung cancer surgery before; 4. Patients who have received radiotherapy or chemotherapy and are not treatment-naive patients.