Segmentectomy Versus Lobectomy for Deep Solid-Dominant Early-Stage NSCLC

SOLID is a multicenter, open-label, randomized, controlled, phase III non-inferiority trial comparing anatomic segmentectomy with lobectomy in patients with deeply located, solid-dominant, clinical stage IA non-small cell lung cancer (NSCLC) measuring \

Inclusion Criteria: 1. Age 18 to 80 years. 2. Solitary pulmonary nodule with whole-tumor maximal diameter \=95%. Preoperative pathologic confirmation is not mandatory, but preoperative or intraoperative pathology should be obtained when technically safe and feasible. 6. Complete staging with thin-slice contrast-enhanced chest CT, whole-body PET-CT, brain contrast-enhanced MRI or CT, and serum tumor markers as appropriate; clinical stage IA (cT1a-bN0M0) without regional nodal or distant metastasis. 7. Cardiopulmonary function sufficient to tolerate both lobectomy and segmentectomy, with FEV1 and DLCO \>=60% predicted. 8. Written informed consent, including special disclosure that final pathology may be benign. 9. Centralized imaging review confirmation by the lead-center technical committee before randomization. Exclusion Criteria: 1. Lesion located in the right middle lobe. 2. Lesion located in the inner two-thirds but adjacent to the lung apex or base and judged suitable for wedge resection. 3. Two or more lesions requiring anatomic resection. One secondary lesion requiring only non-anatomic wedge resection is allowed; two main lesions in the same segment are excluded. 4. Prior ipsilateral lung surgery or another malignancy within 5 years. 5. Severe cardiovascular or cerebrovascular disease or other comorbidity making lobectomy or conversion to lobectomy intolerable. 6. Planned basal segmentectomy (S7-10); proper segmentectomy is permitted.