Patients will be evaluated for inclusion criteria and exclusion criteria, and then they will sign informal consent if desired. He/she will be randomly assigned to the intervention according to a prepared random tables. Patients in the systematically mediastinal lymph node dissection (SLND) group will receive systematically mediastinal lymph node dissection, while those in the non-SLND group will not receive mediastinal lymph node dissection. The primary endpoint is 3-year disease-free survival (DFS).~The sample size was estimated with reference to our previous data, in which the 3-year DFS was 96.6% for patients diagnosed with cT1 ground glass opacity (GGO) dominated invasive lung adenocarcinoma and underwent SLND. We assumed that if 3-year DFS of patients in non-SLND group was over 91.6% , then we would deem the non-SLND group to be non-inferior to the SLND group. The sample size was estimated to be 638.~In order to render the number of recruited patients for each tumor location conform to the actual distribution, we designed a random table for each tumor location. In our previous study, for cT1 GGO dominated invasion lung adenocarcinoma, tumor in the left upper lobe, left lower lobe, right upper lobe, right middle lobe and right lower lobe accounted for 24.7%, 13.2%, 37.6%, 6.6% and 17.9%, respectively. Therefore, the random number table for left upper lobe, left lower lobe, right upper lobe, right middle lobe and right lower lobe included 158 patients, 84 patients, 240 patients, 42 patients and 114 patients, respectively. The total number of patients enrolled was designed to be 638.
Systematically mediastinal lymph node dissection or not in clinical stage T1 ground-glass dominated invasive lung adenocarcinoma: a multi-center, prospective clinical trial