How safe is it to eat meat from an animal that had cancer?

Don't know: As far as i understand, sick animals are not butchered for meat. I don't think you can find an answer to your question.

I advise against it.: The cancer may not only make the meat unsafe, it may be associated with bacterial infection, and parasites that are a direct threat. Understand that this is not a healthy animal, but a diseased and weakened one.