The high-risk group for lung cancer is generally defined as those who are older than 40 years old and have any of the following high-risk factors: 1) smoking more than 20 packs per year or more than 400 cigarettes per year, which is a high-risk group for lung cancer; 2) former smokers who smoked more than 20 packs per year or more than 400 cigarettes per year, but have quit smoking for less than 15 years. Those who have quit smoking but have quit for less than 15 years are also considered high-risk groups for lung cancer; 3, some chronic diseases of lung cancer, including chronic obstructive pulmonary disease, combined with diffuse interstitial lung lesions, combined with old tuberculosis, these patients are also high-risk groups for lung cancer; 4, some people with environmental and high-risk occupational exposure, they are often exposed to some harmful substances, including asbestos, radon, beryllium, these They are also at high risk of lung cancer; 5. People with previous history of malignant tumors or family history of lung cancer are also at high risk of lung cancer.