The causes of lung tumors are complex, and it is currently believed that lung tumors are the end result of the interaction between internal and external factors, and are one or a class of diseases caused by multiple causes, multiple stages and multiple mutations, as follows: 1. Smoking: is one of the most important high-risk factors causing lung tumors. 2. 3. ionizing radiation: long-term exposure to ionizing radiation will greatly increase the probability of lung tumors, especially lung cancer. 4. chronic lung diseases: such as chronic obstructive pulmonary disease, emphysema, tuberculosis, pulmonary fibrosis, are also one of the high-risk factors for lung cancer.