You may want to check your facts as well. Though the link between marijuana and cancer is one that is still very much up for debate there is no doubt that many studies have linked the smoking of cannabis (without tobacco or any other additives) to various types of cancer including lung, testicular, and bladder.
Also, as a previous poster pointed out marijuana does contain carcinogens (pretty much anything that creates smoke does) and on top of that any hot vapor that is inhaled can singe the alveoli of the lungs. In conclusion, feel free to enjoy smoking your marijuana just don’t try to say that it is some magic substance that has no side effects (everything has side effects). At the moment, there is not yet any proven link between cannabis smoking, or any cannabis use, and cancer. Though if any readers can dig up any studies, I might like to read them. Smoking isn’t exactly good for you though. You can now smoke cannabis via a vaporizer, and you inhale almost no smoke. It’s a better way to go. Surely cannabis use has ill effects (especially heavy use does) but cancer doesn’t seem to be one of them.