Usually, when we meet some long-term smoking patients, respiratory doctors will decisively recommend to quit smoking, but some patients will say, “I can’t quit, I’ve been smoking for so long, it will lead to such and such problems after quitting, and I will get lung cancer because of it”, “A certain friend was found to have lung cancer less than 2 months after quitting smoking. “. Is that really true? Actually, no! Scientific research has shown that: smoking causes cancer, especially with the most accurate relationship with lung cancer, and the longer you smoke, the more you smoke, the greater the possibility of cancer. Some people who quit smoking for a year or two or even a month after the onset of lung cancer, and then mistakenly believe that quitting smoking leads to the occurrence of lung cancer. In addition, for those who have been smoking for a long time and are dependent on tobacco, they will indeed feel uncomfortable after quitting, affecting their appetite, energy and sleep, and will experience other discomforts. In fact, the earlier you quit smoking and the longer you quit smoking, the lower the risk of getting lung cancer. When lung cancer is found after quitting smoking for a certain period of time, it is not because quitting smoking has contributed to the occurrence of lung cancer, but precisely because of the long-term damage to the body caused by long-term smoking. In addition, the development of lung cancer is caused by abnormal expression of oncogenes and oncogenes due to the long-term effect of certain high-risk factors, and it takes a long time to develop. Short-term smoking cessation leads to the occurrence of lung cancer is a complete misconception and an excuse made by some tobacco-dependent people who do not want to quit smoking. In addition, some people may ask why some people who smoke do not get lung cancer in their lifetime. It should be said that smoking is the main cause of lung cancer, but not the only cause. The development of lung cancer is multifactorial and multi-step, and the external causes work through the internal causes, so if there are external causes of long-term smoking that do not lead to abnormal gene expression, lung cancer generally does not occur. It is worth mentioning that many long-term smokers, although they do not have lung cancer, but have hypertension, emphysema, diabetes, coronary heart disease, hyperlipidemia, liver cancer, stomach cancer, colorectal cancer and other benign and malignant diseases, therefore, smoking is harmful to quit smoking the sooner the better, it is never too late to quit!