The purpose of this study is to evaluate the safety and effectiveness of a specialized surgical technique called "Septum-guided Segmentectomy" for treating early-stage lung cancer located deep within the lung tissue.Standard surgery for lung cancer often involves removing an entire lung lobe (lobectomy), which can significantly reduce a patient's breathing capacity. For small tumors, removing only a segment of the lung (segmentectomy) can preserve more healthy tissue. However, for tumors located deep in the lung, traditional segmentectomy is technically challenging and risks leaving cancer cells behind.In this study, surgeons will use the natural anatomical boundaries-the intersegmental veins and their surrounding thin membranes (septa)-as a guide to precisely remove the target lung segment. This "septum-guided" approach aims to ensure the cancer is completely removed while maximizing the preservation of healthy lung function.Participants will be followed for 3 years after surgery to monitor for cancer recurrence and assess their long-term recovery.

This is a single-center, prospective, single-arm clinical trial (SGS2512) designed to validate the oncological safety and technical feasibility of septum-guided segmentectomy for deep-seated, solid-dominant early-stage non-small cell lung cancer (NSCLC).Background: While segmentectomy has been proven comparable to lobectomy for small peripheral NSCLC (≤2 cm), its application for deep-seated lesions (inner 2/3 of the lung) remains controversial. Traditional methods rely on fixed safety margins, which are often difficult to achieve in deep regions without sacrificing excessive lung tissue. This study utilizes the "intersegmental septum" as a natural barrier to define the resection boundary.Key Procedures:Surgical Technique: All procedures are performed via single-port VATS or Robot-assisted Thoracic Surgery (RATS). The core technique involves the identification and exposure of the intersegmental veins and the corresponding septa to guide the separation of the target segment.Intraoperative Second Registration: After surgery begins but before the segment is resected, a second check is performed. If frozen section pathology reveals lymph node metastasis or if the anatomical structure is unsuitable for segmentectomy, the procedure will be converted to a standard lobectomy to ensure patient safety.Follow-up: Patients will undergo regular chest CT scans, tumor marker tests, and pulmonary function tests at 1, 6, 12, 18, 24, 30, and 36 months postoperatively.Statistical Design:

The study uses an A'Hern single-stage design to evaluate the primary endpoint. With a null hypothesis (H0) of 3-year RFS ≤ 81% and an alternative hypothesis (H1) of 3-year RFS ≥ 91%, a total of 89 participants are planned for enrollment to ensure 80 evaluable cases. Data analysis will be performed using R software (version 4.0 or above).

Inclusion Criteria:

• Age 18-80 years
• Clinical stage IA (cT1a-bN0M0)
• tumor diameter ≤ 2 cm
• Pathological feature: Solid-dominant lesion (CTR > 0.5)
• Tumor location: Deep-seated within the lung parenchyma (inner 2/3), defined as the tumor center being located in the inner 2/3 region of the lung field on axial, coronal, and sagittal CT views
• ECOG Performance Status: 0-1
• Pulmonary function: FEV1 ≥ 60% predicted and DLCO SB ≥ 60% predicted
• Participants must be willing and able to provide written informed consent

Exclusion Criteria:

• Multiple pulmonary nodules or evidence of distant metastasis
• Intraoperative confirmation of lymph node metastasis (N1/N2) or pleural dissemination
• History of previous ipsilateral lung surgery
• History of other malignant tumors within the past 5 years
• Presence of severe cardiovascular or cerebrovascular diseases that preclude surgical tolerance
• Pregnancy or breastfeeding

Individual participant data that underlie the results reported in this article, after de-identification (text, tables, figures, and appendices), will be shared with researchers who provide a methodologically sound proposal.

Beginning 6 months and ending 36 months following article publication.

Proposals should be directed to the corresponding author (Junfeng Geng). To gain access, data requestors will need to sign a data access agreement.

None (Open Label)