Primary bronchial lung cancer, referred to as lung cancer, is a malignant tumor originated from bronchial mucosa or glands. At present, the incidence rate of lung cancer is increasing year by year, and the information released by the World Health Organization (WHO) shows that lung cancer ranks the first place in the global cancer both in terms of incidence rate and mortality rate. British oncologist R. Peto predicts that if our country doesn’t control the smoking and atmospheric pollution in a timely manner, the number of incidence of lung cancer will exceed 1 million each year in 2025, and our country will become the first country of lung cancer in the world. British oncologist R. Peto predicted that if China does not control smoking and air pollution in time, by 2025, the annual incidence of lung cancer in China will be more than 1 million, which will make China the first big country in the world. Numerous researches show that smoking is the primary cause of lung cancer, and compared with non-smokers, the risk of lung cancer in smokers is 4-10 times higher on average, and in heavy smokers, it can be 10-25 times higher. Why does smoking cause lung cancer? Cigarettes produce smoke when they are lit, but do you know how terrible the smoke from burning cigarettes is? Research has found that smoke contains more than 3,000 kinds of toxic chemicals, the most important of which are nicotine, carbon monoxide, cyanide, the presence of a variety of carcinogens in the smoke tar, radioactive isotopes and heavy metal elements, etc., and has been clearly identified carcinogenic substances such as benzo(a)pyrene, nitrosamines, β-naphthylamine, cadmium, radioactive polonium, etc., and phenol compounds and other cancer-promoting substances. Cigarettes are so terrible, it can be imagined that if smoking for a long time, the carcinogenic substances in the smoke repeatedly stimulate the bronchial mucosa or glands, resulting in the risk of lung cancer will be higher and higher, the close correlation between the amount of smoking and lung cancer is by no means alarmist, but the obvious quantity-effect relationship, the younger the age of starting to smoke, the longer the time of smoking, the more the amount of smoking, the higher the incidence rate of lung cancer, the study found that people who have smoked from It is found that the incidence rate of lung cancer in people who have smoked for more than 15 to 25 years is 4 times higher than that of non-smokers, and the incidence rate of lung cancer in people who have smoked for 20-60 years is 100 times higher than that of non-smokers. The cancer risk of a cigarette is equivalent to 0.01-0.04mGy of radiation. Smoking 20 cigarettes a day is equivalent to receiving a radiation dose of 1.2mGy, while taking a chest X-ray in the hospital, the radiation dose is only 0.4mGy. Therefore, there is no doubt that smoking will lead to lung cancer. Does passive smoking cause lung cancer? Of course, it is found that passive smoking or environmental smoking is also one of the most important causes of lung cancer. Among non-smoking wives whose husbands are smokers, the risk of lung cancer is two times higher than that of wives of non-smoking families, and the risk increases with the amount of smoking of husbands, and passive smoking or environmental smoking is what we call second-hand smoke. Reports show that 82% of passive smokers are exposed to secondhand smoke in the home, 67% in public places, and 35% in the workplace. Among them, due to different age, gender and occupation, the proportion of people exposed to second-hand smoke in various places is also different, passive smoking women 90% are exposed to second-hand smoke in the home, men aged 20 to 59 years old in public places and workplaces exposed to second-hand smoke in the highest proportion. Although secondhand smoke is less concentrated than direct inhalation of airway smoke, it still reaches the value of the injury domain; secondhand smoke tends to “enjoy” the repeated bombardment of multiple smokers, so the smoking time is long, and the injuriousness is very prominent; a person who smokes will result in a room full of passive smoking; the smoke from the combustion of the cigarettes will remain in the room for a long time, and it is not easy to disperse, all of these factors contribute to the harm of secondhand smoke in the home. All of these factors have led to the second-hand smoke on human health is a growing threat, so the public places to ban smoking is extremely important prevention and control measures. Smoking is so horrible that those who have been checked for lung cancer for a long time have instantly fallen into the doldrums, and those who have been checked for lung cancer for a long time have been rejoicing as if they have been reborn. Can quitting smoking reduce the risk of lung cancer? January 24, 2013, the New England Journal of Medicine published an article, according to the United States more than 200,000 people survey, smokers than never smokers mortality rate is three times higher (from smoking-related tumors, cardiovascular and respiratory diseases), life expectancy is shorter than 10 years, however, if you quit smoking before the age of 35 years old, you can make up for the 10 years back, before the age of 55 years old to quit smoking can be found back in the 6 years, so it seems that quit smoking can indeed reduce the risk of lung cancer, as a rebirth. It seems that quitting smoking can indeed reduce the risk of lung cancer. At present, domestic and foreign research on the results of smoking cessation is more or less exciting, and there is clear evidence that after quitting smoking, the risk of lung cancer decreases year by year, and it can be halved after 1-5 years of quitting smoking, and the incidence of lung cancer after 10-15 years is equivalent to that of lifelong non-smokers. Do smokers and non-smokers suffer from the same lung cancer? Although both are lung cancers, we can tell you clearly that they are not the same. Lung cancer can be categorized into squamous carcinoma, adenocarcinoma, large cell carcinoma, and small cell carcinoma according to the type of pathology. Smokers are more likely to develop squamous carcinoma and small cell carcinoma, while non-smokers are more likely to develop adenocarcinoma. Lung cancer is the result of gene mutation, and each cancer cell may have multiple gene mutations. Some studies have found that the number of gene mutations in smokers’ lung cancer is at least ten times higher than that of non-smokers, and the types of gene mutations are also different, and the studies have found that there are three types of gene mutations related to lung cancer, namely, KRAS, EGFR, and ALK, and the main mutations in smokers’ lung cancer are KRAS mutations, and the mutations in non-smokers’ lung cancer are EGFR In smokers, KRAS mutation is the main cause of lung cancer, while in non-smokers, it is EGFR and ALK. Currently, targeted drugs mainly target EGFR and ALK, while there is no specific drug for KRAS mutation, which is an important reason why smokers’ oral targeted drugs have poor efficacy. What factors increase the carcinogenic effect of smoking? Exposure to occupational carcinogenic factors, the occupational factors that can lead to lung cancer have been clearly identified as asbestos, arsenic, nickel, chromium, coal tar, mustard gas, trichloromethyl ether, chloromethyl ether and radon and radon daughters gas produced by the decay of radioactive substances such as uranium and radium. Air pollution, the polluted air contains 3,4-benzopyrene, arsenous oxide, radioactive substances, nickel, chromium compounds and non-combustible aliphatic hydrocarbons and other carcinogenic substances, air pollution is serious in big cities, the daily inhalation of the air contains the amount of benzo(a)pyrene can be more than 20 cigarettes, and increase the carcinogenic effect of cigarettes. Ionizing radiation, large doses of ionizing radiation can cause cancer, the source of ionizing radiation in the population 49.6% from the natural world, 44.6% of the bit of medical irradiation, from the X-ray diagnostic ionizing radiation can be accounted for 36.7%, for example, if a person is always to go to the hospital to receive a high dose of CT examination, then even if there is no cancer, it will also induce cancer over time.