Lung cancer generally refers to primary bronchial lung cancer, which is one of the malignant cancers. Common manifestations include coughing and coughing up sputum, and in severe cases, blood in sputum or a small amount of hemoptysis, and in advanced stages, a large amount of hemoptysis and difficulty in breathing. I. Why lung cancer occurs? The causes of lung cancer are very complicated, mainly environmental factors and personal factors. Environmental factors are due to the development of industry, atmospheric pollution has become a serious problem, such as nitrosamines, asbestos, chromium, nickel and petroleum waste gas, which are scattered in the air and water and enter the human body and cause lung cancer over time. Smoking is the main cause of personal factors (smoking index is equal to the number of cigarettes smoked per day multiplied by the number of years of smoking, and those greater than 400 are significantly associated with the development of lung cancer). According to a survey, people who smoke are 8.8 times more likely to develop lung cancer than non-smokers. In addition, tobacco contains the carcinogenic substance N-nitrosonitrate, a nitrosamine, which can become a carcinogenic active substance after activation. According to Chinese medicine, lung cancer belongs to the category of lung accumulation and interest ben, which is mostly caused by wind, cold, summer, humidity, dryness and fire, which invade the lungs for a long time and cause lung cancer. At the same time, patients with weak constitution, endocrine disorders, low immune function, or congenital defects, malnutrition, smoking, and too much of the seven emotions can also lead to lung cancer. With the increasing severity of urban air pollution and the significant increase of smoking and passive smoking, the incidence of lung cancer is getting higher and higher. How to prevent lung cancer? 1. Quit smoking: this is the most effective way to prevent lung cancer. Don’t smoke passively either. Establishing no-smoking areas in public places is a good way to prevent passive smoking. 2. Diet should prohibit moldy and spoiled food: eat less pickled food. When eating, should chew slowly, do not eat too hot food. 3, control fat intake: fat intake should be controlled at less than 30% of total calorie intake, that is, daily intake of animal and vegetable fat 50 ~ 80 grams. Eat more fresh vegetables and fruits, coarse grains, etc.: Research has confirmed that eating more green leafy vegetables and tomatoes (tomatoes) has a significant protective effect on lung cancer prevention. 5.Pay attention to environmental health: pay special attention to ventilation in the bedroom and kitchen. 6.Cultivate an optimistic and open-minded personality: avoid overexertion. At the same time, it is necessary to take appropriate exercise, such as running, walking, playing ball, tai chi, etc. 3. How to detect lung cancer early? First of all, we should insist on health checkup every year, and at least take orthogonal and lateral chest radiographs during the checkup; if smokers have smoked for more than 20 years or more than one pack per day, they should have low-dose spiral CT of chest if they have the conditions; they can also be screened by tumor marker examination to detect early lesions from molecular biology perspective. Secondly, pay attention to your physical condition in general. Once there is an irritating, uncontrollable dry cough, or changes in the regularity or characteristics of cough, especially for smokers, you should be alert; if there is blood in the sputum or blood sputum, you should go to the hospital for medical treatment.