Lung cancer

Lung cancer is one of the most dangerous malignancies with the fastest increase of morbidity and mortality. In the past 50 years, many countries have reported a significant increase in the incidence and mortality of lung cancer. The incidence and mortality of lung cancer in men account for the first place among all malignant tumors, while the incidence and mortality of lung cancer in women account for the second place. The cause of lung cancer is still not completely clear, a large number of data show that long-term heavy smoking and the occurrence of lung cancer has a very close relationship. Previous studies have shown that long-term heavy smokers are 10 to 20 times more likely to develop lung cancer than non-smokers, and the younger they start smoking, the higher the risk of lung cancer. In addition, smoking not only directly affects my physical health, but also has a negative impact on the health of the surrounding population, leading to the passive smokers lung cancer prevalence increased significantly. The incidence of lung cancer in urban residents is higher than that in rural areas, which may be related to air pollution and soot containing carcinogens in urban areas. Therefore, non-smoking should be promoted and urban environmental sanitation should be strengthened.

The cause of
Smoking is 1.
Currently, smoking is considered to be the most important risk factor for lung cancer. There are more than 3,000 kinds of chemicals in tobacco, among which the multi-chain aromatic hydrocarbons (e.g., benzopyrene) and nitrosamines have strong carcinogenic activity. Multi-chain aromatic hydrocarbons and nitroso amines can lead to DNA damage in bronchial epithelial cells through a variety of mechanisms, leading to the activation of oncogenes (such as Ras) and the inactivation of tumor suppressor genes (such as p53 and FHIT), thus leading to cell transformation and ultimately cancer.

Occupational and environmental exposure
Lung cancer is the most important type of occupational cancer. An estimated 10% of lung cancer patients have a history of environmental and occupational exposure. The following nine occupational carcinogens have been proved to increase the incidence of lung cancer: by-products of aluminum, arsenic, asbestos, bis-chloromethylether, chromium compounds, coke stoves, mustard gas, nickel impurities, vinyl chloride. Long-term exposure to beryllium, cadmium, silicon, formalin and other substances can also increase the incidence of lung cancer. Air pollution, especially industrial waste gas, can cause lung cancer.

3. Ionizing radiation
The lungs are more sensitive to radiation. The first evidence of lung cancer caused by ionizing radiation came from the data of the schneeberg-joakimov mine, where the concentration of radon and its progeny in the air was high, which induced mostly small-cell carcinoma of bronchi. In the United States, it has been reported that 70% ~ 80% of the miners who mined radioactive ores died of occupational lung cancer caused by radiation, mainly squamous cell carcinoma. The onset time from the initial contact was 10 ~ 45 years, the average time was 25 years, and the average onset age was 38 years. The incidence of radon and its daughters began to increase when the accumulation of radon and its daughters exceeded 120 working days (WLM), and increased by 20-30 times when the accumulation of radon and its daughters exceeded 1800WLM. Exposure of mice to gas and dust from these mines can induce lung tumors. Lung cancer has increased significantly among Japanese atomic bomb survivors. Beebe found a significant increase in lung cancer deaths among survivors who were less than 1400m away from the detonation, compared to those who were between 1400m and 1900m away and 2000m away, during a lifetime follow-up of Hiroshima bomb survivors.

4. Previous chronic lung infection
Such as tuberculosis, bronchiectasis patients, bronchial epithelium in the chronic infection process may be transformed into squamous epithelium resulting in cancer, but relatively rare.

5. Genetic and other factors
Familial aggregation, genetic susceptibility and reduced immune function, metabolism, endocrine dysfunction may also be in
Play an important role in the occurrence of lung cancer. Many studies have demonstrated that genetic factors may play an important role in populations and/or individuals susceptible to environmental carcinogens.

Air pollution
The incidence of lung cancer in developed countries is high, the main reason is due to the industrial and transportation developed areas, oil, coal and internal combustion engines and other combustion dust and asphalt road produced by containing benzopyrene carcinogenic hydrocarbon and other harmful substances pollution of the atmosphere. Air pollution and smoking on the incidence of lung cancer may promote each other, synergistic effect.