The only known way for cancer to spread from one person to another is through organ or tissue transplantation, but the risk is extremely low, around two cases per 10,000 transplants.
Certain viruses and bacteria, like HPV and H. pylori, can increase cancer risk, but the cancers they cause cannot spread from person to person.
Misconceptions like cancer spreading through close contact, sharing personal items, or exposure to air are unfounded, as cancer cells cannot survive outside the body.
Cancer clusters and higher rates in families are not due to contagion but rather shared genes, lifestyles, and environmental exposures.
Avoiding contact with someone who has cancer due to fear of contagion is unnecessary and can make them feel isolated, as cancer is not spread through casual contact.