In my clinical work, I am often asked quietly by family members whether cancer is contagious because there are often many couples suffering from the same cancer, and they worry that if they catch it while taking care of their patients, they will not die. In fact, this is an unfounded worry. Scientists still have no evidence to prove that cancer is contagious. Cancer itself is not directly contagious because cancer cells do not release infectious factors, but during its development certain tumors can be associated with infectious diseases and viral infections. For example, many patients with liver cancer have a history of preexisting hepatitis B, which itself is infectious. 99.8% of cervical cancer patients are infected with HPV virus, and EBV virus is associated with the occurrence of nasopharyngeal cancer, therefore, we can say: some tumors are caused by infectious diseases, but direct transmission of tumors generally does not exist.