According to the latest national statistics, the incidence and mortality rate of lung cancer in major cities in China has ranked first among all kinds of tumor diseases. Early detection and diagnosis as well as early treatment are the most important ways to improve the survival rate of lung cancer patients. In terms of diagnosis, low-dose spiral CT thin-layer scan can already detect microscopic lesions and improve the diagnosis rate of lung cancer. However, not everyone needs to undergo thin layer CT scan, who are the suitable groups? That is, those who are at high risk of lung cancer. People with high risk of lung cancer are those who have a high incidence of lung cancer and a high relative risk of lung cancer. So, who are the high-risk groups of lung cancer? 1. Middle-aged and elderly people belong to the high-risk group of lung cancer: Generally speaking, the incidence rate of lung cancer rises gradually for people older than 55 years old, and reaches its peak when they are 75-80 years old. However, the incidence of lung cancer has a tendency of lowering the age group. 2.People who have been smoking for a long time and smoke more than 20 cigarettes a day: Cigarettes contain harmful substances, especially tar and nicotine, which are strong carcinogens, and the toxic substances in cigarettes also gradually destroy some villi and increase the secretion of mucus, so that chronic diseases occur in the lungs, which can easily lead to bronchitis and cancer. Many times higher than others. 3.People who live in areas with serious air pollution: People who live in areas with serious environmental pollution for a long time have been found that 80% of malignant tumors are induced by environmental factors, and there are a lot of carcinogenic substances in the environment where human beings live, which is the main reason for the increasing incidence of cancer year by year. 4.People with long-term exposure to radiation: Those who receive excessive radiation exposure inside and outside the body, such as individuals who work in metal mines and have long exposure to inorganic arsenic, asbestos, chromium, nickel, etc., and lack of protection, these people have a higher risk of lung cancer than the general population. 5. People who are exposed to soot or oil smoke for a long time: such as workers who are exposed to gas, asphalt, coke making, cooks and housewives who are exposed to kitchen fumes for a long time, these people have a higher incidence of lung cancer than the general population. 6. People with a history of chronic lung diseases: chronic bronchitis, tuberculosis, chronic obstructive pulmonary disease, etc. 7.People with family history of heredity and those who are in long-term sadness, depression, self-suppression and introversion. For the prevention of lung cancer in high-risk groups, firstly, it is to get rid of modifiable risk factors, such as smoking and radiation; secondly, to strengthen their own protection awareness and timely treatment of chronic lung diseases; again, to have regular CT examination, preferably once a year.