Lung cancer is not a contagious disease, but it is not without the possibility of transmission. There are conditions for lung cancer to be contagious, firstly, the source of infection, the susceptible population and the transmission route, one of these three conditions is not necessary, otherwise there will be no contagion. Moreover, we should know that there are many differences between lung cancer and tuberculosis, although they are both lung problems, lung cancer is not contagious in most cases. Cancer cells excreted through sputum rapidly degenerate and necrotize due to evaporation of sputum water, etc. Even fresh sputum needs to be given various nutrients and specific conditions in order for cancer cells to grow and multiply outside the body. Scientists often need to go through a lot of hard work in order to cultivate a living cancer cell to succeed, so cancer is not contagious. Besides, patients with lung cancer must pay attention to the three early stages, that is, early detection, early diagnosis and early treatment, so as not to miss the best time for treatment. Many people take surgical treatment, which is often effective when taken early, and the earlier the treatment, the less chance of its recurrence. However, lung cancer is a disease that can be inherited, and people with a family history have a greater than normal chance of getting lung cancer. Although lung cancer seems to have a family aggregation phenomenon, there is no evidence to date that there is a specific susceptibility gene for lung cancer. A growing body of research supports the idea that lung cancer is caused by gene-environment interactions, and that genetic variations in carcinogen metabolism, DNA repair, and genes controlling cell proliferation and apoptosis may be important genetic susceptibility factors for lung cancer related to smoking. Therefore, the key measure to prevent and reduce the occurrence of lung cancer is to quit smoking. However, we need to understand that just because a disease is heritable does not mean it is inherited. Infectious diseases are caused by the spread of microorganisms, including bacteria and viruses, between populations, such as tuberculosis and hepatitis. In contrast, hereditary diseases are caused by blood ties that cause many people in a family to suffer from the same disease. If one of the parents suffers from a certain type of cancer, their children are more likely to suffer from the same type of cancer, which means that cancer friends often have an obvious family history of tumors. The survey results show that the incidence rate of cancer patients is higher among those who are related than those who are not, and the incidence rate of close relatives is higher than that of distant relatives, while there is no significant difference between paternal and maternal relatives, indicating that the incidence of cancer is related to genetic factors.