The stage of lung cancer depends on two aspects: the size of the tumor and its spread. If the lung cancer itself is in situ, the tumor is small and not accompanied by mediastinal lymph node metastasis, it is a tumor in situ and generally belongs to early stage and can be given surgery. If the lung cancer has not spread to the surrounding lymph nodes, including supraclavicular lymph nodes and cervical lymph nodes, and only metastases in the ipsilateral hilar lymph nodes, it can also be classified as early or intermediate stage, and can be treated surgically after adequate evaluation by thoracic surgery. If the lung cancer has spread to the contralateral lymph nodes and distant multi-organ metastasis, it is an advanced stage and must not be in the early stage, and there is no indication for surgery.