This study aims to investigate whether segmentectomy had non-inferiority long-term oncological effects (disease-free survival and overall survival) compared with lobectomy in the treatment of patients with early-stage non-small cell lung cancer ≤ 2 cm in the middle third of lung field.

Nowadays, the role of segment resection in the treatment of non-small cell lung cancer ≤ 2 cm in the outer third of the lung field has been evaluated in multiple studies. Recently, professor Hisao Asamura released the long-term results of the JCOG0802 project in AATS 2021. Segmentectomy had a higher 5-year overall survival (94.3% vs. 91.1%) than lobectomy (P < 0.001) for non-small cell lung cancer ≤ 2 cm (CTR > 0.5) in the outer third of the lung field. However, a substantial portion of lung nodules was not located in the outer third, but the middle third of the lung field. Whether segmentectomy has non-inferiority long-term oncological effects compared to lobectomy for early-stage non-small cell lung cancer ≤ 2 cm in the middle third of lung field remains unclear. This randomized controlled trial study aims to investigate whether segmentectomy has non-inferiority long-term oncological effects compared to lobectomy for early-stage non-small cell lung cancer ≤ 2 cm in the middle third of the lung field.

Inclusion Criteria:

1. Patient aged 18-75 years old;
2. 6 mm ≤ tumor size ≤ 20 mm;
3. 0.25 < CTR < 1;
4. Center of tumor located in the middle third of the lung field;
5. ECOG score of 0,1 or 2;
6. Lung function (FEV1 ≥ 1 L and ≥ 70%);
7. Both lung segmentectomy and lobectomy could achieve R0 resection;
8. No serious cardiopulmonary complications, and could withstand both lung segmentectomy and lobectomy;
9. No hilus pulmonis and mediastinal lymph node metastasis and no distant metastasis;
10. Single tumor nodule or the concomitant nodule < microinvasive tumor;
11. Written informed consent.

Exclusion Criteria:

1. The tumor nodule is located in right middle lobe;
2. A history of other malignancies in the last 5 years (exclusion of early-staged thyroid cancer);
3. Have received preoperative anti-tumor therapy, including prior chemotherapy, radiation therapy, target therapy and so on;
4. A serious mental illness;
5. Pregnant and lactating women;
6. Congestive heart failure, myocardial infarction, severe stenosis of coronary artery within recent 6 months;
7. With the history of cerebral infarction or cerebral hemorrhage within 6 months;
8. With the history of sustained systemic corticosteroid therapy within 1 month;
9. The predicted surgical margin is less than 2 cm or the maximum diameter of the tumor at the 3D-CTBA
10. Other unsuitable situations;