I have this silly theory about cancer that it is the smoke that gives you cancer not the food itself.
So meat gives you cancer because you eat it cooked, particularly food that is eaten on barbecues, whereas stuff you eat raw (fruit, vegetables, nuts) doesn't.
Smoking obviously therefore gives you cancer because you are inhaling smoke (if my theory is correct smoking paper with nothing in it would give you cancer, the nicotine is irrelevant) and hence smoking weed also gives you cancer.
Cannabis oil is not smoked and therefore this could make all the difference.