This study aims to evaluate the non-inferiority in recurrence-free survival and overall survival of segmentectomy compared with lobectomy in patients with lung adenocarcinoma ≤ 2 cm with micropapillary and solid subtype negative by intraoperative frozen sections.

At present, the technology of intraoperative frozen section has gradually matured, which can diagnose the benign and malignant tumors and guide the resection strategy for peripheral small-sized lung adenocarcinoma. Travis et al. reported high specificity of intraoperative frozen section in the identification of micropapillary components, confirming that intraoperative frozen section may guide the selection of surgical procedures. However, there is still little evidence weather segmentectomy is appropriate for invasive adenocarcinoma without micropapillary patterns. This prospective and multi-center study was aimed to evaluate the non-inferiority in recurrence free survival and overall survival of segmentectomy compared with lobectomy in patients with lung adenocarcinoma (≤ 2 cm) not including micropapillary components.

Inclusion Criteria:

• Patient aged 20-79 years old, both male or female;
• Tumor size <= 2cm on preoperative CT scan;
• Peripheral solitary nodule or the associated lesion is MIA or less invasive lesion;
• Preoperative CT indicated that the nodules were non-pure glass nodules (consolidation to tumor ratio >= 0.25);
• Intraoperative frozen section confirmed invasive lung adenocarcinoma with micropapillary and solid subtype negative (<= 5%);
• Intraoperative frozen section indicated the resection margins was free of tumor cells;
• Lung function could withstand both lung segmentectomy and lobectomy (FEV1 > 1.5L or FEV1% >= 60%);
• Eastern Cooperative Oncology Group, 0 to 2;
• Volunteer to participate the trial and sign the informed consent, able to comply with the follow-up plan and other program requirements.

Exclusion Criteria:

• Radiological pure ground glass nodules (consolidation to tumor ratio < 0.25);
• The nodule is close to the lung hilus and is unable to perform segmentectomy;
• Intraoperative frozen section confirmed with micropapillary and solid subtype positive (> 5%);
• Intraoperative frozen section confirmed adenocarcinoma in situ and minimally invasive adenocarcinoma;
• Preoperative imaging examination or EBUS indicated lymph node positive metastasis;
• Preoperative imaging examination revealed distant metastasis;
• Patients with severe damage to heart, liver and kidney function (grade 3 ~ 4, ALT and/or AST over 3 times the normal upper limit, Cr over the normal upper limit);
• Patients with other malignant tumors;
• Pregnant, planned pregnancy and lactating female patients (urine HCG>2500IU/L is diagnosed as early pregnancy);
• Prior chemotherapy, radiation therapy or any other therapies were performed; 12 participated in other tumors within three months of relevant clinical subjects;
• Those who have participated in other tumor-related clinical trials within three months;
• Those are not suitable for participating in trials according to investigator's assessment.

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