Clinical study found that factors that lead to cancer by internal and external factors of the double impact, is very complex. General external causes, including chemical carcinogens, ionizing radiation, a variety of environmental carcinogens, viruses and other factors, internal factors include the body’s cells, DNA change v change, genetic characteristics, immune function, hormone levels change. 4 internal and external factors in the interaction, the complex and lengthy occurrence of cancer, as experiences start (initiation), the promotion (promotion) and evolution (progression) three stages.
What specific factors led to aspects of cancer?
Factors according to cause cancer role in the carcinogenic process can be divided into start its agents, accelerators, complete carcinogens, and four types of incomplete carcinogens. Activator, is that certain chemical, physical or biological factors, they can change the cell’s genetic material, composition or structure of DNA, usually the first contact to complete, this process is generally irreversible. Accelerator itself can not induce tumors, and only then start the agent role to promote the role of agents repeatedly, only to promote tumorigenesis. There are many types of tumor promoters, such as certain hormones, drugs, croton oil.
Some tumor promoters induce a tumor only play a catalytic role, while the other – kind of tumor does not work, such as saccharin can promote the occurrence of bladder cancer, but can not afford to promote the role of induced liver cancer: Benzene Bobby properly state the occurrence of liver cancer, but does not affect the incidence of bladder cancer. The role of some very strong carcinogen, both started and the promotion of two functions, alone can cause cancer, called complete carcinogens such as polycyclic aromatic baby, aromatic rubber, nitrite rubber.