A cancer vaccine is a vaccine used to prevent or treat cancer. Preventive cancer vaccines, such as the HPV vaccine and the Hepatitis B vaccine, block infection of the causative agents, as do traditional vaccines such as polio vaccine. Therapeutic cancer vaccines, which are newer and chiefly experimental, coax a person's immune system into recognizing and destroying malignant cells without harming normal cells; they are being investigated for the treatment...
My sympathy for your pyr. You didn't say how old he is.
All the questions you asked are things that it's the responsibility of your VET to tell you those...