I've been wondering the same thing about vapes for a while now. Is it true that they are not damaging to your body. That's what everyone says, but what proof is there? What studies have been done to prove this?
If your a heavy smoker, vape for a week straight and see how your lungs feel. IMO that proof enough that its better for you then smoking. Note this is only true if you use the vape to only vaporize and don't turn it all the way to the top heat like some people insist on doing. If you go with a vape might i recomend one with a digital temp control, or getting an IR thermometor from an auto supply store. You can also spend some time trying to just tune in the right setting, once you have it just leave it there and you'll use all the thc in the weed. Remember you may be getting a hit even if you can't see anything, its not smoke.
but i know for sure there are many articles on marijuana and cancer you can find (i wrote a paper on it last year) but it does take a bit of digging to find the more reliable medical journals and articles