Lung cancer examination is mainly based on three major means: First, chest CT. People over 40 years old can have low-dose chest CT screening once a year, if suspicious small nodules or ground glass shadows are found on the lungs, they should be alerted if they have a long history of smoking or family history of lung cancer. Secondly, hematological examination, after the development of lung cancer reaches a certain level, tumor markers in blood will be elevated. Different pathological types of lung cancer have corresponding tumor markers, such as carcinoembryonic antigen, squamous cell carcinoma antigen or neuron-specific enolase. Third, the final diagnosis is pathological examination. After the above two conditions are found, fiberoptic bronchoscopy or CT-guided puncture biopsy can be used to finally confirm the diagnosis.