To date, there is no evidence that cancer is contagious. Three conditions are necessary for transmission: source of infection, transmission route and susceptible population, none of which is necessary. Clinical data prove that cancer patients themselves are not the source of infection. Experts have done experiments in which cancer tissue was removed from cancer patients and implanted directly into mice, and the cancer cells did not survive and grow. Although it is currently believed that the development of certain cancers is associated with certain viruses, such as: cervical cancer and HPV virus, nasopharyngeal cancer and EBV virus, leukemia and HTLV1 virus, and liver cancer and hepatitis virus. However, it has not been confirmed that infection with certain viruses necessarily leads to certain cancers. Besides, cancer is not classified as an infectious disease in the world, and patients are not admitted and treated with the same isolation measures as infectious diseases. The incidence of cancer is not higher among medical staff in oncology hospitals than in the general population. Animal experiments also prove that when cancer-stricken animals and healthy animals are kept together for a long time, after repeated observation and examination, no contagion is seen either. When family members or friends have cancer, don’t worry about the contagion, but should spend more time with them and dedicate a warm and loving heart, so as to help patients recover from the disease as soon as possible.