Patients and methods: The study will include surgical patients from six medical centers in Taiwan. All of the patients will receive complete study about the surgical risk and tumor staging before surgery. The patients will receive general anesthesia and pulmonary resection as the standard procedures including division of pulmonary vessels and bronchus. Either VATS (Video-assisted thoracoscopic surgery) or open surgery is acceptable for the surgical approaches. The patients will be randomly assigned to lobectomy and sublobar resection groups. Two cm of resection margin will be obtained in each patient in the sublobar resection group by wedge resection or segmentectomy. Standard lymph node dissection including the pulmonary hilum and mediastinum will be done in both groups of patients. For suspicious of pulmonary hilum or mediastinal lymph node metastasis, frozen pathological examination will be requested.