Cancer cells are mainly caused by genetic mutations and physical, chemical, viral and other cancer-causing factors. 1. Genetic mutation: Cancer cells will be produced after mutation of genetic material such as DNA in human body. 2. Physical factors: Usually mechanical stimulation, trauma, ultraviolet rays, burning, radiation and other physical factors are cancer-causing factors that can induce certain tumors. For example, if patients repeatedly receive X-ray irradiation or radionuclide examination, it can increase the risk of developing tumor. And tuberculosis patients can also induce breast cancer in case of repeated chest X-ray examination. 3. Chemical factors: Usually, chemical substances are widely found in food, pesticides, medical drugs, etc., which are very harmful to human body and have a relatively long latency time in the body. Generally, salted and smoked foods contain more carcinogenic substances and are more abundant, while moldy foods often contain carcinogenic substances, such as aflatoxin. 4. Virus carcinogenicity: recent scientific research shows that there are nearly 30 kinds of animal tumors are caused by viruses, and some human tumors are also closely related to viruses. Usually, the antibodies of related viruses can be found in the serum of some patients with cervical cancer, liver cancer, nasopharyngeal cancer, etc. Some data show that schistosomiasis can induce liver cancer and colorectal cancer, etc. It is recommended that patients pay more attention to their own care. It is recommended that patients pay more attention to their own care, and if cancer cells are detected in the body, they should actively seek medical treatment.