The tnm clinical staging of lung cancer is based on three important parameters to determine whether lung cancer is largely early or advanced after a lung cancer patient has undergone a thorough examination. These three parameters are the size and location of the primary lesion of lung cancer and its invasion of surrounding tissues and organs (t), local lymph node metastasis (n), and whether distant metastasis (m) has occurred. The tnm grading system was formed based on the status of three parameters: t, n, and m. The grading of t included 1, 2, 3, and 4; the grading of n included 0, 1, 2, and 3; and the grading of m included 0, 1, and x (i.e., whether distant metastasis was not determined). According to different tnm grading status of patients and different combinations of 3 parameters of tnm, such as T2N0M0, T4N3M1, etc., they can be further graded as one of 7 stages, such as stage IA, stage IB, stage IIA, stage IIB, stage IIIA, stage IIIB, stage IV, etc. Among them, stage IA, stage IB, stage IIA, stage IIB, stage IIIA belong to early stage; stage IIIB, stage IV belong to late stage.