To date, there is no evidence that cancer is contagious. Three conditions must be present for transmission: a source of infection, a means of transmission and a susceptible population, all of which are indispensable. Clinical data prove that cancer patients themselves are not the source of infection. Experts have conducted experiments in which cancerous tissues taken from cancer patients were directly planted into mice, and the cancer cells did not survive and grow. Although it is currently believed that the occurrence of certain cancers is related to certain viruses, such as: cervical cancer and HPV virus, nasopharyngeal cancer and EB virus, leukemia and HTLV1 virus, liver cancer and hepatitis virus. However, it has not been proved so far that if you are infected with certain viruses, you will definitely get a certain kind of cancer. Besides, cancer has not been listed as an infectious disease in the world, and no isolation measures like infectious diseases have been taken for admitting and treating patients. The incidence rate of cancer among medical and nursing staff of oncology hospitals is not higher than that of the general population. Animal experiments have also proved that when cancer-stricken animals and healthy animals are kept together for a long period of time, after repeated observation and examination, no contagious phenomenon is seen. When family members or friends have cancer, they should not worry about contagion, but should spend more time with them and dedicate warmth and love, which is conducive to the early recovery of patients’ conditions.