The goal of this clinical trial is to investigate the role of segmentectomy in clinical T1c (2-3 cm) non-small cell lung cancer (NSCLC). The main questions we aim to answer are:

1. Is segmentectomy non-inferior to lobectomy in cT1c NSCLC in terms of overall and recurrence free survival?
2. What are the mortality and morbidity rates of segmentectomy compared to lobectomy?

Researchers will compare segmentectomy and lobectomy in terms of overall and recurrence free survival.

Participants will:

• Undergo either pulmonary lobectomy or segmentectomy with mediastinal nodal dissection
• Be followed up with a chest CT in every 3 months in first year, every 6 months in second year and every year for following 3 years

Inclusion Criteria:

• Clinical T1c NSCLC
• Parenchymal nodule >2 cm in diameter
• Parenchymal nodule ≤3 cm in diameter
• Consolidation / Tumor Rate (CTR) ≥ 0.50
• Definitive pathological diagnosis of NSCLC preoperative or intraoperatively
• No evidence of distant metastasis
• No evidence of N2 disease
• Adequate pulmonary functions for lobectomy or segmentectomy

Exclusion Criteria:

• Pure GGO lesions
• Pathologic diagnosis other than NSCLC
• Technically not suitable for simple or complex segmentectomy, or lobectomy
• Evidence of distant metastasis
• Pathologically confirmed N2 or N3 disease
• Major comorbidity that precludes surgery
• Intraoperative mediastinal nodal dissection of less than 3 lymph node stations
• Prior malignancy in five years