The pathogenesis of lung cancer is complex, as follows: 1) smoking is the primary cause of lung cancer, including the influence of second-hand smoke; 2) atmospheric pollution and ionizing radiation: it has been reported in both the United States and Japan, and the incidence of lung cancer in Japan increased significantly after the atomic bombing of Nagashima; 3) chronic infections: current studies have found that tuberculosis and chronic obstructive pulmonary disease are related to the development of lung cancer; 4) genetic mutations and hereditary factors: clinical findings show that lung cancer has a tendency to gather in families; 5) the influence of cooking fumes, which may be related to the increasing incidence of female adenocarcinoma.