The prognosis of patients with lung cancer (including NSCLC and SCLC) is determined by a combination of clinicopathological characteristics of the patients. In addition, certain biochemical indicators (white blood cell count, calcium blood count, and blood tumor marker levels (e.g., CEA) have also been shown to be significantly associated with the prognosis of lung cancer patients. Currently, clinicopathologic staging, or TNM staging, remains the primary and most stable predictor of survival time for lung cancer patients. The prognosis of lung cancer patients depends largely on the TNM stage of the tumor at the time of disease detection. Patients with different clinical stages have significantly different prognosis. According to the results of a meta-analysis of 94,703 NSCLC patients reported in the AJCC 8th edition tumor staging manual in 2017, the 5-year survival rate for stage IA patients is about 80, including 92, 83, and 77 for stage IA1, IA2, and IA3 patients, respectively; 68 for stage IB patients; and 55 for stage II patients. For stage III patients, the 5-year survival rate drops to about 20; while for stage IV patients, the 5-year survival rate is less than 5, and the median survival is only 7 months. SCLC is more malignant than NSCLC and more prone to recurrence and metastasis, so the survival period of SCLC patients is significantly shorter than that of NSCLC. The prognosis of lung cancer patients with various TNM stages reported in China is similar to that of AJCC, and a comprehensive analysis of several large-scale statistics from 2000 to 2012 shows that the 5-year survival rate of NSCLC patients in China is about 75 for stage I, 55 for stage II, 20 for stage III, and 5 for stage IV. For SCLC patients in China, the above figures are 45, 25, 8, and 3, respectively.