Early and late stages of lung cancer are mainly staged according to TNM staging. Early stage of lung cancer refers to lung cancer without lymph node metastasis or distant organ metastasis, which is usually referred to as stage IA or IB, while middle stage is usually referred to as stage II or III, in which patients usually have lymph node metastasis without other distant metastasis, while patients with advanced stage usually have distant organ metastasis, which is also referred to as stage IV in TNM staging. TNM staging is used by International Union Against Cancer (IUAC) to stage lung cancer according to tumor, lymph node metastasis and distant metastasis, which is applicable to small cell lung cancer and non-small cell lung cancer, and it can be used as a reliable guideline for lung cancer staging, and it is recommended that people diagnosed with lung cancer should go to the hospital for treatment in a timely manner.