The formation of human tumors, i.e. the transformation from normal cells to cancer cells, is a rather long process. Usually, it takes years of exposure to carcinogens to cause progressive and severe atypical proliferation of cells in tissues and organs. It takes many years of exposure to carcinogens to cause progressive and severe atypical proliferation of cells in tissues and organs before they become cancer. This period of physical induction is usually as long as 15-30 years. There are many reasons for the occurrence of tumor in human body, but in general, the occurrence of tumor has a certain relationship with the nature, intensity and duration of action of exogenous carcinogens, and also has an important relationship with the internal factors of human body. Exogenous carcinogenic factors include physical carcinogenic factors, chemical carcinogenic factors, etc. Endogenous factors include endocrine dysfunction, neuropsychological factors, immune status and genetic factors, etc. Although the presence of exogenous carcinogenic factors can easily lead to cancer, some people develop cancer while others do not under the same conditions of exposure to the same quality and quantity of carcinogenic factors, which shows that although exogenous factors are important, they must be based on endogenous factors. The progress of molecular cell research has made people understand that cell is a complex and fine structure of life. Many carcinogens affect the genes in the cell nucleus, or act on the surface of the cell membrane, affecting the metabolic links of the cell through physical and biochemical changes in the membrane. As a result of these effects, intracellular enzyme system and nucleus function are disturbed, resulting in the initiation of division and promotion of deoxyribonucleic acid synthesis in quiescent or normally dividing cells, leading to a series of changes in cell division, differentiation and growth behavior, causing cancer. The latest oncogene theory suggests that tumors occur due to malfunctioning cell proliferation and differentiation. When cell division increases and differentiation or death decreases, the number of undifferentiated ultimate cells increases, i.e., the phenomenon of malignant growth occurs. The proliferation of cells is often caused by an imbalance in regulation. The oncogene doctrine elucidates a number of genetic changes that affect key control points of cell proliferation or carcinogenesis and suggests that two types of genes are directly involved in tumorigenesis: oncogenes (tumor) genes and tumor suppressor genes. Oncogenes (tumor) genes are genes that have the potential to induce malignant transformation of cells under natural or experimental conditions. The products of expression of oncology (tumor) genes play a positive regulation of cell proliferation, when they undergo structural changes or are overexpressed, the pro-growth effect is too strong and can cause excessive cell proliferation, while the products of the other class of tumor suppressor genes play an inhibitory role in cell proliferation, when their structure and function are altered, the negative regulation of cell proliferation is lost and the information that makes cells proliferate also occurs. With changes in either or both genes, i.e., there is a possibility of tumorigenesis.