The cause of malignant tumors is not yet fully understood. Through years of epidemiological studies and experimental and clinical observations,, the environment and people behavior play an important impact on the occurrence of malignant tumors.
It is estimated that more than 80% of malignant tumors are associated with environmental factors.
Various environmental and genetic carcinogenic factors may induce non-fatal DNA damage to cells in a synergistic or sequential manner, thereby activating proto-oncogenes or (and) inactivating tumor suppressor genes, and with the changes of apoptotic regulatory genes and ( Or) DNA repair gene, as a result cells are transformed. Transformed cells can be polyclonal hyperplasia. During a long multi-stage evolution process, one clone relatively unrestrictedly amplifies. With the additional mutation, a sub-clone of different characteristics is selectively formed to obtain infiltration and transfer capacity, finally malignant tumors will be formed. Therefore, the tumor is essentially a genetic disease.
Genetically inherited tumors are only a few uncommon tumors, and the role of genetic factors in most tumors is increasing the tendency of the tumor development and the susceptibility to carcinogenic factors, such as colonic polyposis, breast cancer, and gastric cancer.
Congenital or acquired immunodeficiency prone to malignant tumors, such as hepatitis B protein deficiency patients susceptible to leukemia and lymphoid hematopoietic system tumors. However, most of the malignant tumor occurs to the people with normal the immune function. The main reason is that the tumor can escape the immune system monitor and destroy the body’s immune system.
In addition, endocrine factors, external chemical, physical, biological factors are important pathogenic factors of cancer. Another important factor of cancer is age. Over time, our cell damage will accumulates and chronic inflammation will occur over time. Thus the risk of multiple cancers also increases with age. Besides, the impact from the basic state of our body, lifestyle, psychological and emotional aspects of the impact can not also be ignored.