hello
asthma and lung cancer are completly unrelated....imagine a person with asthma and a person without....smoke the same amount for years and years....they have the same chance of getting cancer.....its completly about your cells and genetics

Cancer is one of the risks of smoking....if you dont want to get cancer don smoke.....although you can still get cancer (from a zillion things nowadays...so....lol)

as for other methods of using weed....i would have to say eating it or vap'ing it are the best (safest) way....as far as i know.....

Sorry not really much help but......there you go