The exact cause of lung cancer so far short of understanding. After years of extensive research, the following factors currently recognized cause of lung cancer is closely related.
(A) smoking, according to national survey data showed that a large number of causes of lung cancer and smoking cigarettes very close relationship. Increased incidence of lung cancer and cigarettes were paralleled an increase in sales. Cigarettes contain benzopyrene and other carcinogens. Inhalation of cigarette smoke or animals can be induced respiratory smear tar and skin cancer. The habit of smoking lung cancer incidence rate 10 times higher than non-smokers, smoking, a higher incidence of large quantity, 20 times higher than non-smokers. End of this century, Western European countries with the increasing number of women smokers, the incidence of lung cancer in female patients was significantly increased. Clinically diagnosed cases of lung cancer, cigarette smoking more than 20 cigarettes per day, which lasted more than 30 years, accounting for about 80%. 20 ~ 30 years, smoking is very serious, nearly 3 billion people in the habit of smoking. Beijing, Tianjin, Shanghai and other big cities adult male smoking rate of nearly 50%, nearly 5% of women, and there are many young smokers, such as not taking the necessary measures to control, discourage smoking, then the next 10 30 years, China will further increase the incidence of lung cancer. Long-term smoking can lead to proliferation of bronchial epithelial cells, squamous epithelial Health, induced squamous cell carcinoma or undifferentiated small cell carcinoma. No Smoking habits were, though it may be suffering from lung cancer, but cancer is more common.
(B) air pollution a high incidence of lung cancer in industrialized countries, high urban than in rural areas, factories, mines and areas of high residential areas than in lung cancer etiology, mainly due to the developed areas of industry and transport, petroleum, coal combustion and internal combustion engines and asphalt roads, etc. generate dust containing harmful substances such as benzopyrene carcinogenic hydrocarbon pollution of the atmosphere related. Survey material shows high concentration of benzopyrene in the atmosphere region also increased the incidence of lung cancer. Air pollution and smoking cigarettes on the incidence of lung cancer may promote each other and from the synergy.
(C) occupational factors 30 years of this century, the European Schneeberg mining literature have lung cancer incidence reports. After years of research, long-term exposure has been recognized as uranium, radium and other radioactive materials and their derived properties, carcinogenic hydrocarbons, arsenic, chromium, nickel, copper, tin, iron, coal tar, asphalt, oil, asbestos, mustard gas and other substances, can induce lung cancer, mainly squamous cell carcinoma and undifferentiated small cell carcinoma.
(D) chronic lung diseases such as tuberculosis, silicosis, pneumoconiosis and lung cancer and other can co-exist. The high incidence of cases of cancer in healthy subjects. In addition chronic inflammation of the lung and bronchial pulmonary fibrosis scarring lesions in the healing process may lead to squamous metaplasia or hyperplasia, on this basis, some cases can develop into cancer.
Lung cancer etiology (e) internal factors such as family, human genetics, and immune function of reduced metabolic activity, endocrine disorders, such as lung cancer may also play a role in promoting.