Lung cancer is divided into stage I, stage II, stage III and stage IV, and each stage can be divided into stage a and b respectively. Cancer is prone to metastasis and requires comprehensive examination of possible metastatic sites for accurate staging. Different stages of lung cancer lead to different treatment methods. Stage I and II are mainly surgery, stage III is mainly combined with radiotherapy and chemotherapy, and stage IV is mainly drug therapy. Common analysis is as follows: 1. Stage I: usually the tumor does not exceed 3cm in diameter in the lung, and there is no lymph node metastasis, this kind of patient belongs to relatively early stage. 2. Stage II: the tumor is larger or lymph node metastasis has already appeared in the lung. 3. The tumor has metastasized to other organs, such as brain, liver, bones and other parts.