Segmentectomy Versus Lobectomy for Lung Adenocarcinoma ≤ 2cm

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.