Cancer is indirectly contagious. Some cancers can spread from person to person through genetic means - that is, through inheritance. It does not spread through direct contact from hugging, kissing or sex. There are many other mechanisms that can result in the formation of cancer such as those mentioned by Dr. Oz & Dr. DeVita (HPV, HIV, Hepatitis B,C etc.) Scientist are learning more about circulating tumor cells and cancer stem cells which is an unknown problem in the future if they are ever found in the U.S. blood supply. No one is screening for them currently, and blood transfusions are relatively safe for the most part. The best way to reduce your risk (outside of genetics) of acquiring cancer is to adopt a healthy lifestyle by stop smoking, and excessive alcohol use. Reduce your body fat (body mass index) and exercise plenty as we know that obesity is a risk factor for the development of several cancer types.
More Answers from Simeon Jaggernauth, DO