We eat all kinds of foods stuff. Meats, vegetables, fruits. Most of them can have cancers of one kind or another. For eg. Trees can get cancers so i am assuming fruits do too.
This question therefore asks can cancers from animals pass on to humans after consumption.
Or if consuming human flesh from cancer sufferer can it pass on to the consumer, not wishing to debate cannabalism here.
Plant “cancers” are usually caused by viruses, and I don’t know of any plant viruses that are capable of infecting humans, so I’d say the chance of catching cancer from your lunch apple are quite low.
There are cancers that are transmissible between animals (of the same species); there is no common cancer of this type in humans, but there are very, very rare reports of humans acquiring tumors by getting pieces of someone else’s tumor tissue into their body, through tissue transplants or in at least one case a wound (a surgeon who accidentally stabbed himself while operating on a cancer patient). I suspect that eating cancerous tissue wouldn’t do much unless you had a wound in your mouth; otherwise the tissue would just get digested like any other piece of meat.
And there are human viruses that cause cancer, but I don’t believe any of them is capable of being transmitted through food.
Well, Tasmanian Devils can get cancer from biting Tasmanian Devils. Which is technically sort of like eating.
Oops, I see that’s already been posted. So a different answer: cancer is caused by the genetic controls that limit cell growth being broken. So for a transmissible cancer to survive, it would have to be a cell type that is compatible with your body–something that your own immune system doesn’t attack and is allowed to grow unchecked. It would be acting as some sort of endoparasite, not transforming your own cells to cancer. So, I’d say the more different two species, the less likely cancer would result, unless it somehow managed to by chance evolve defenses against your immune system (as other endoparasites have.)