Cancer Causes 
The human immune system can destroy cancer cells, but when the human body, weakening or anti-cancer inhibition, the proliferation of cancer cells will continue to go on to form a visible clinical cancer.
The medical profession at home and abroad have confirmed that the human 80% to 90% of cancer associated with the external environmental factors, that is, the human living environment in the physical, chemical and biological factors are closely related to the occurrence of cancer. The adverse environmental protection system against the body would be a buffer or resistance, its role can be eliminated or weakened. When the cancer-causing factors, the cumulative effect of too strong or too large, while the human immune insufficiency or physical repair functions deficiencies cases, there may be cancer.
Current environmental pollution increased, with the human living environment worsening, and increasingly close contact with cancer-causing factors. The stability of human cells can only be relative, the human cell gene change is inevitable and unavoidable, but that does not mean that cancer can not be overcome and people do nothing for cancer. In fact, each of us the existence of the human body are all different parts of the number of cancerous cells, but only a few cancerous cells can develop into cancer, the majority of cancerous cells, or organism promptly remove, or not independent ability to divide a long period of latency, will not endanger human health. With the medical progress and development, as well as in-depth cancer research, it is the causes of cancer has been an unprecedented understanding of occupational cancer have basically been able to prevent some cancers in the general population have also been able to prevent and governance more.