T2N0M0 in T2N0M0 refers to the size of the mass, which should be >3cm or <5cm according to current analysis. n0 means no lymph node metastasis and M0 means no distant metastasis. Lung adenocarcinoma T2N0M0 should be classified as stage IB or IIA in the staging system, but it is also related to the size of the mass, if the size of the mass is 3-4cm, it belongs to stage IB, if it is 4-5cm, it belongs to stage IIA. Lung adenocarcinoma and squamous lung cancer staging are the same. According to the current lung cancer staging standard, there are four stages: I, II, III and IV, of which stage I is early stage, stage II is middle stage, stage III is middle and late stage, and stage IV is called advanced stage, according to the size of the lump, the involved area, lymph node metastasis status, lymph node metastasis site, whether there is distant metastasis, and the overall situation of multi-organ metastasis.