That is correct, cancer is not contagious. Cancer is a disease that occurs when cells in the body grow and divide uncontrollably, often forming tumors. While some infections or diseases can be contagious and spread from person to person, cancer is not caused by a virus, bacteria, or other infectious agent. Instead, cancer is typically caused by genetic mutations or other changes in the body’s cells that can occur spontaneously or be triggered by environmental factors such as exposure to certain chemicals or radiation. While cancer itself is not contagious, certain viruses such as HPV or hepatitis B and C can increase a person’s risk of developing certain types of cancer..