Approximately 80% of malignancies are disseminated, meaning that there is no specific, definite predisposing factor. Lung cancer is one such type of malignancy for which there is no definite cause and therefore no definite way to predict and prevent it. However, through extensive epidemiological studies, we have identified a number of environmental factors that may increase the chance of developing lung cancer. Tobacco exposure remains by far the number one risk factor for lung cancer. It is important to note that not only smokers themselves are at high risk for lung cancer, but also those who inhale secondhand smoke. The harmful substances in tobacco can damage the cells in the lungs, especially the epithelial cells that cover the inner surface of the bronchi. These cells will break away from their normal orderly self-renewal and go on a crazy path of malignant proliferation. The longer and more severe the exposure to tobacco, the higher the chances of developing lung cancer. Although 87% of lung cancer patients can trace their past medical history to smoking or exposure to secondhand smoke, only 1 in 10 of all smokers will get lung cancer. But this does not mean that the other 9/10 smokers are safe; in fact smoking is also a predisposing factor for other malignant diseases such as esophageal and bladder cancer. Of course smoking can also cause heart disease, emphysema, chronic bronchitis and other common diseases. In the United States, 400,000 people die each year from tobacco-related diseases. Therefore, the United States for tobacco control is increasing, the price of a pack of Marlboro in New York has increased to $13 under heavy taxation, for the tobacco-hit low-income class, which is undoubtedly a price that can not be regularly consumed, while the middle and upper income classes are increasingly strong health awareness is driving them away from tobacco. This will gradually curb the proliferation of tobacco from all income levels. In China, it is the opposite, the high-income class has high-priced cigarettes to show their status, the low-income class has low-priced cigarettes to meet consumption, in short, the concept of all people. In the West, there is no difference between expensive and cheap tobacco, all are marked with a striking brand of harm, and the price is basically the same. WHO’s 2013 tobacco control report states that tobacco causes about 6 million deaths and more than $500 billion in economic losses each year. Without rapid implementation of the framework convention, up to 1 billion people will die from tobacco this century. Tobacco use remains the leading preventable cause of death worldwide, but there are actually effective and cost-efficient ways to combat the deadly tobacco epidemic. Radon Radon is a colorless, odorless radioactive gas that is a product of the natural decay of the radioactive substance uranium. It exists in soil and rocks, and is ubiquitous although its content is extremely low. However, when the concentration of radon reaches a certain level, it will damage the lung cells. The human body is susceptible to lung cancer when exposed to higher than normal radon environment, especially among the smoking population. Radon is considered to be a pollutant that affects indoor air quality worldwide. In the United States, radon is the second largest lung cancer triggering factor after tobacco, and 15,000 to 22,000 die every year because of it. It is estimated that one out of every 15 households has excessive radon levels (>4 picocuries per liter). Radon can be monitored by simple monitoring equipment, and once the items with high radon concentration are removed, the resulting hazards will disappear as well. Asbestos and other industrial carcinogens A carcinogen is any substance that increases the chance of cancer when exposed to it. Asbestos is a notorious carcinogen, therefore, asbestos for construction has been completely abandoned at present, and buildings containing asbestos that have been built are being removed by all means. However, asbestos has been used extensively in industry and construction over the past few decades because of its good insulation and fire protection. Asbestos fibers disintegrate very easily and become suspended particles in the air and stain clothing. However, when inhaled into the lungs, asbestos particles can significantly damage alveolar cells and induce lung cancer and malignant mesothelioma (a malignant tumor of the pleura with a very poor prognosis). In addition to asbestos, there are many other carcinogens that increase the chance of lung cancer: arsenic, chromium, nickel, diesel combustion exhaust, soot, tar, etc. The risk of lung cancer induced by the above carcinogens is even higher than that of smoking, except that the population exposed to tobacco is huge. Air pollution There is a mild increase in the incidence of lung cancer in an environment with severe air pollution, but this factor should not exceed 1% of all lung cancer patients, but smokers are more vulnerable to air pollution. Family history If your parents, siblings have lung cancer, your chances of developing lung cancer should be slightly higher than the normal population. However, it should be noted that over 80% of all tumors are disseminated cases, meaning that there is no clear genetic factor. We have not yet found a genetic predisposition to lung cancer, so there is generally no need to be overly concerned because someone else in your family has lung cancer. Personal health history People who have had lung cancer in the past are more likely to develop new lung cancer than normal people. History of chest radiation therapy can increase the chance of lung cancer, such as previous chest radiation therapy for lymphoma or breast cancer, and should be monitored closely for the appearance of lung tumors thereafter, especially for smokers. Emphysema and chronic bronchitis can increase the chances of lung cancer. The worse your lung function is, the more likely you are to develop lung cancer. In China, the incidence of previous and invisible tuberculosis is very high, especially now among people aged 50-70 years, and previous old tuberculosis damage, especially scarring, also increases the chances of lung cancer. Gender The gender predisposition to lung cancer is still debated, but women are more likely than men to develop lung cancer when exposed to risk factors, especially to smoking. A large number of women in China are exposed to secondhand smoke from their own spouses. Hormonal differences may be the main reason why women are more vulnerable to various carcinogens, especially tobacco. Minorities Black male smokers in the United States are 45% more likely to develop lung cancer than white men. We are a multi-ethnic country and there have been no findings of differences in lung cancer incidence between races. Age Two-thirds of lung cancer patients are older than 65 years, with an average age at diagnosis of 71 years, and less than 3% of all lung cancer patients are under 45 years of age. Diet and exercise Some reports seem to suggest that low intake of fruits and vegetables increases the chance of lung cancer in people who smoke, and WHO studies show that eating the equivalent of 4 cups of vegetables and fruits per day can reduce the incidence of lung cancer by 12% worldwide. More exercise also appears to be an effective means of reducing the incidence of lung cancer. Therefore, a good lifestyle habit is the best way to reduce the incidence of lung cancer.