After many years of clinical research physicians have found that the major cancer-causing factors and to explore the following six categories: tobacco, alcohol, environmental, viral infections, occupational factors, genetic factors.
A major carcinogens of tobacco carcinogens as early as 50 years in the 20th century, experts made it clear that the risk of lung cancer in smokers, non smokers, 10 times, the risk increases with the increase in smoking large. Smoking not only lung cancer, can also cause other cancers, it makes the risk of occurrence of laryngeal cancer increased 8 times, oral cavity and pharynx cancer increased to 4 times to 3 times the esophageal and gastric cancer, bladder cancer and membrane adenocarcinoma to 2 times. Tar cigarette smoke in a chemical carcinogen, therefore, the overall proportion of cancer caused by smoking is about 30%.
Two major carcinogens, alcohol, wine and pay long-term carcinogenic factors liver cancer, esophageal cancer , gastric cardia, gastric cancer, oral cancer and the Ministry of throat cancer on a great relationship. Increase in liver cancer and liver cells may be involved in alcohol metabolism. Esophageal cancer, responsible for the door, stomach and mouth, the throat cancer is also associated with smoking. The dual effect of drinking and smoking is not just a simple overlay, may also act synergistically. Because those who are often paid a lot of wine, smoking, therefore, in the smoking-related cancers, alcohol is alcohol on the carcinogenic mechanism may be the direct effect of epithelial tissue, such solvents may contribute to chemical carcinogens in the smoke the target tissue release.
Three major carcinogens, environmental carcinogens such cancer-causing factors is the environment polluted by carcinogens. People in life are exposed to cancer-causing factors, such as through the air, soil, water and other hazards to enter the human body. Environmental pollution caused by the cancer mortality of the total cancer mortality by about 20%. Atmospheric pollution and lung cancer more closely. Many studies agree that China, lung cancer incidence, urban than rural areas, the greater metropolitan higher incidence of lung cancer.
Four major carcinogens, viral infections in human tumors on the virus role in the past, there have been more controversial, many people hold negative views. But now, the virus's role in tumorigenesis has been affirmed. And human tumor virus closely related to hepatitis B virus, papilloma virus, EB virus and human T cell leukemia virus (HTLV-I HTLV – II), human immunodeficiency virus (HIV) and so on. For example, herpes simplex-like virus and human papilloma virus cervical cancer are two closely related human DNA virus; human T cell leukemia virus type I virus (HTLV-I) can cause a special type of human leukemia, which T-cell leukemia / lymphoma (HTLL).
Five major cancer-causing factors, occupational factors such factor is the labor and production environments in the human existence can cause cancer of the factors of workers. Occupational carcinogens and the relationship between the occurrence of human cancer has been relatively clear, such as asbestos workers, lung cancer and mesothelioma, vinyl chloride polymerization workers in the hepatic angiosarcoma and rubber industry workers exposed to solvents such as myeloid leukemia . In recent years, there is growing concern about the environment and human health of chemical carcinogens and their relationship, and had undertaken extensive research.
Six major carcinogenic factors, genetic factors environmental carcinogens in human tissues in the role of host genetic quality will no doubt vary with the change. Occasionally found in some tumors with familial or genetic phenomenon, and sometimes even this form of expression was very obvious. Therefore, the relationship between tumor and genetic factors is currently an important topic in cancer research, I believe that in the near future to achieve a breakthrough to clarify its mechanism, and promote faster development of cancer prevention.