The most effective examination method for early lung cancer is low-dose CT scan of the lung, especially for middle-aged women with long-term smoking history or second-hand smoke, they need to have regular CT scan of the lung. If it is lung cancer, further whole body PET-CT examination will be done to clarify whether there are lymph node metastasis or mediastinal lymph node metastasis, distant metastasis, especially bone metastasis. If there is no lymph node metastasis, mediastinal lymph node metastasis or bone metastasis, it is early stage lung cancer. At this time, radical surgical resection can be done, and the 5-year survival rate after surgery is over 80%, or even long-term survival.