All the 1 joint = 5 ciggs bullshit is false. And wether it promotes cancer or not, it won't do it nearly as fast as cigarettes. Plus, there is a whole mess of chemicals in Marijuana that contributes to that system in your body that regulates fatigue and hunger and stuff... we don't know what is in it exactly... or at least what alot of those other chemicals do. But most promote good health, though we all know that smoking anything can't be good for your lungs.