Lung cancer is a malignant tumor of the respiratory system, and long-term heavy smoking is closely related to the occurrence of lung cancer. Lung cancer mainly includes lung squamous carcinoma, lung adenocarcinoma and lung small cell carcinoma, among which lung squamous carcinoma is most closely related to smoking. The process of smoking can produce a lot of carcinogens, such as nicotine and tar, which can stimulate squamous epithelial metaplasia of bronchial mucosa and further carcinogenesis, while squamous carcinoma is mainly caused by squamous epithelial metaplasia. Therefore, squamous lung cancer is most closely related to smoking, and the relationship between the two is further confirmed by the fact that squamous lung cancer is commonly found in male patients who smoke.