Complete lung cancer lymphadenectomy in patients without nodal metastasis may not improve survival and would increase operative duration and cause damage to mediastinal structures.The investigator's previous retrospective study showed tumors with adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) or lepidic predominant adenocarcinoma (LPA) histology had zero mediastinal nodal involvement. Tumors in the apical segment of upper lobes had zero inferior mediastinal nodal involvement.