This study aims to evaluate the superiority in recurrence-free survival of lobectomy compared with segmentectomy in patients with lung adenocarcinoma ≤ 2 cm with micropapillary and solid subtype positive 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 whether segmentectomy is appropriate for invasive adenocarcinoma without micropapillary patterns. This prospective and multi-center study was aimed to evaluate the superiority in recurrence free survival and overall survival of lobectomy compared with segmentectomy in patients with lung adenocarcinoma (≤ 2 cm) containing positive micropapillary components.

Inclusion Criteria:

• Tumor size ≤ 2 cm;
• Solitary tumor and located in the outer third of the lung field;
• Preoperative CT indicated that the nodules were single nodules or Concomitant nodules was less than minimal invasive adenocarcinoma;
• Intraoperative frozen section confirmed invasive lung adenocarcinoma and with micropapillary and solid patterns positive (>5%);
• Confirmation of R0 status by intraoperative frozen section analysis;
• Pulmonary function could withstand both segmentectomy and lobectomy (FEV1 > 1.5 L or FEV1% ≥ 60%);
• Sufficient organ function;
• Performance status of 0,1 or 2；
• Written informed consent.

Exclusion Criteria:

• The tumor is close to the hilum, which cannot perform segmentectomy ;
• Patients suspected of lymph node positive by preoperative examination, including CT scans and mediastinal lymph node biopsy;
• Evidence revealed locally advanced or metastatic disease;
• Intraoperative exploration revealed accidental pleural dissemination.
• Patients with severe damage to heart, liver and kidney function (grade 3 ~ 4, Alanine aminotransferase (ALT) and/or Aspartate aminotransferase (AST) over 3 times the normal upper limit, Cr over the normal upper limit).
• Patients concomitant with other malignant tumors；
• Patients had prior chemotherapy, radiotherapy or molecular targeted therapy for this malignancy.
• History of severe heart disease, heart failure, myocardial infarction within the past 6 months.
• The patients who were not suitable for inclusion by researchers' evaluation.

clinical stage IA patients with Lung Adenocarcinoma ≤ 2cm as well as micropapillary and solid Subtype positive (>5%) by frozen sections