The first two sentences are so badly wrong I don’t even know which thread to pull on to unravel your thought processes. (I can’t speak for the third).

Do you believe that “natural” is tautologically equivalent to “good”?

Are cancerous cells unhealthy to eat?

I don’t know, but I do know some tumours are transmissible (even interspecies) so I wouldn’t want to rule it out: https://en.wikipedia.org/wiki/Clonally_transmissible_cancer

I expect thorough cooking to prevent this sort of thing, but some people do eat raw flesh deliberately.