Actually there are several cancers that are viral based. One of the most well-known ones afflicted AIDS patients who after they got the AIDS virus ended up getting very noticeable distinctive unusual skin cancers called some kind of sarcoma. I forget what it was. When AIDS was first happening in the 1990s I remember very well the discussions that this caused a cancer that was contagious and it was the first known type of cancer that was contagious. Now you don't need to tell me that the cancer wasn't directly caused by the virus. I know that. The virus reduced your immune system which left your body open to the cancer. Nonetheless the cancer itself was contagious because of a virus.

The other contagious cancer I know of is the well-known cancer that young girls are being told to get vaccinated against. It's the uterine cancer caused by that HPV virus.