Gene mutation is a factor in the formation of cancer cells, which may also be induced by genetic factors, external environmental stimuli such as radiation and chemical substances. 1. Gene mutation: When the proto-oncogene or oncogene is mutated in the process of cell replication, the cell will grow uncontrollably, i.e. cancer cell. 2. Hereditary factors: If the elders in the family suffer from certain malignant tumors, and a certain locus carrying the susceptibility gene of such tumors is inherited, the chance of cancer cell development in the offspring will be greater than that of other people. 3. External environmental stimulation: External environmental stimulation may also promote the generation of cancer cells, such as rays, radiation, chemical substances and other stimuli, which are more harmful to human body, and it is recommended to stay away from them as far as possible. In addition to genetic factors and hereditary factors that cannot be changed, we should pay attention to a healthy lifestyle in our daily life.