1.Smoking In 1922, Hampeln found that continuous smoking and inhalation of dust could stimulate the bronchial epithelium to induce cancer. 1924, Moller used tar on the back of rabbits and found a slight increase in the incidence of lung cancer. Smoking is now considered to be the most basic high-risk factor for lung cancer. There are more than 3000 chemicals in tobacco, and multi-chain aromatic hydrocarbons (e.g., benzo(a)pyrene) have strong carcinogenic activity. It can act on certain specific enzymes within human tissues (especially lung tissues) and produce mutations in cellular molecular structures (e.g., DNA), possibly with mutations in K-ras. 2. Occupational and environmental exposure It is estimated that up to 15% of lung cancer patients have a history of environmental and occupational exposure. There is sufficient evidence to confirm that the following nine industrial components increase the incidence of lung cancer: by-products of aluminum products, arsenic, asbestos, bis-chloromethyl
ether, chromium compounds, coke ovens, mustard gas, nickel-containing impurities, and vinyl chloride. Long-term exposure to beryllium, cadmium, silicon, formalin and other substances also increase the incidence of lung cancer. In addition, air pollution, especially industrial waste gas, are all high-risk factors for lung cancer. 3.Radiation Uranium and fluorite miners exposed to inert gas radon gas, decaying uranium by-products, etc., have significantly higher incidence of lung cancer than others, but personnel of ionizing radiation will not increase the incidence of lung cancer. 4.Chronic infection of lung Such as tuberculosis, bronchial dilatation, etc., the bronchial epithelium may transform into squamous epithelium in the process of chronic infection and eventually cause cancer, but such cases are rare. 5.Intrinsic factors Family, genetic and congenital factors as well as lowered immune function, metabolic and endocrine dysfunction may also be high risk factors for lung cancer. 6.Atmospheric pollution The high incidence of lung cancer in industrially developed countries, higher in cities than in rural areas, and higher in factories and mines than in residential areas, is mainly due to the pollution of the atmosphere with harmful substances such as benzopyrene carcinogenic hydrocarbons produced by the combustion of oil, coal and internal combustion engines and asphalt road dust in industrial and traffic developed areas. The survey material shows that the incidence of lung cancer increases in areas with high concentration of benzo(a)pyrene in the atmosphere. Atmospheric pollution and paper cigarette smoking may contribute to each other and play a synergistic role in the incidence of lung cancer.