The chance of lung cancer caused by smoking is closely related to the amount and duration of smoking. The law of 20, that is, a smoker who smokes 20 cigarettes a day for 20 years is 20 times more likely to get lung cancer than a non-smoker, which means that smoking is the main risk factor for lung cancer. In addition to smoking, family history of lung cancer, environmental pollution, dust or radioactivity also increase the chance of lung cancer, so it is more important to prohibit smoking or quit smoking as soon as possible to avoid the occurrence of lung cancer if you have a family history of lung cancer. Currently, lung cancer has the highest incidence and mortality rate in the world and is one of the major malignant tumors threatening health. Therefore, quitting smoking as early as possible is very beneficial to reduce the incidence of lung cancer, and smokers need to undergo strict annual lung cancer screening.