It is well known that smoking is the most important risk factor for lung cancer, and the process of smoking can produce more than 40 kinds of carcinogenic substances, among which the main ones closely related to lung cancer are polycyclic aromatic hydrocarbons, benzene, arsenic, propylene, nicotine (nicotine), carbon monoxide, and tobacco tar. mutation and inactivation of certain oncogenes. Smoking is defined as smoking more than 1 cigarette per day for more than 6 months. In the study, the risk of lung cancer was found to be 20.4 times higher than normal in men who smoked more than 2 packs per day. The greater the amount of cigarettes smoked and the longer the duration of smoking, the greater the risk. more than 90% of lung cancers are due to active smoking or passive secondhand smoke. There is evidence that the risk of lung cancer increases by 20-30% for people who live with smokers and thus breathe secondhand smoke. By stopping smoking before the onset of lung cancer, lung tissue can slowly return to almost normal. Stopping smoking at any age can reduce the risk of lung cancer, heart disease and stroke. Even after a diagnosis of lung cancer, stopping smoking can help improve a patient’s respiratory and general health and reduce the likelihood of a second lung cancer, while increasing the likelihood of success of current treatment. Besides smoking, there are other risk factors that may lead to lung cancer, including: Environmental factors: Radon is an odorless radioactive gas produced during the natural decay of uranium. Areas with relatively high levels of radon gas in the work or living environment (such as uranium mining areas) will increase the risk of lung cancer. People who are exposed to dust or asbestos at work will also have an increased risk of lung cancer. History of respiratory diseases: History of previous lung diseases (asthma, chronic obstructive pulmonary disease, pneumonia and tuberculosis) is a risk factor for lung cancer, with tuberculosis being the most closely related. Air pollution: the level of pollutants in the air is directly proportional to the probability of developing lung cancer. every 10 micrograms increase in 1 cubic meter of air is associated with an 8% increase in the probability of developing lung cancer. The increased incidence of lung cancer in women is now thought to be more closely related to kitchen fumes. Psychological factors: poor psychological adaptability, long-term mental depression, and significant type A personality (meaning fast-moving, impatient, aggressive, and excitable) can increase the risk of lung cancer. Dietary nutritional imbalance: intake of more vegetables and moderate amount of fresh fruits has a protective effect on lung cancer; the greater the intake, the more obvious the protective effect. Vegetables and fruits mainly contain vitamin A, vitamin C, vitamin E and trace elements such as selenium, germanium, platinum, magnesium and zinc, which have the functions of inhibiting DNA amplification of cancer cells and blocking synthesis of carcinogenic substances, respectively.