Station 4L Lymph Node Dissection

This multicenter, prospective, randomized clinical trial will enroll adults aged 18 to 75 years with resectable clinical stage I (T1-T2aN0M0) invasive non-small cell lung cancer presenting as a single solid nodule (consolidation-to-tumor ratio 1.0) in the left lung. After intraoperative frozen-section confirmation of invasive non-small cell lung cancer and completion of standard lung resection and systematic mediastinal lymph node dissection, participants will be randomly assigned 1:1 either to undergo station 4L lymph node dissection or to omit station 4L dissection. The primary hypothesis is that omitting station 4L dissection is noninferior to performing it with respect to 3-year disease-free survival. Secondary outcomes include 3-year overall survival, perioperative complications, 90-day mortality, and station 4L nodal metastasis.