Something like 80% of lung cancers can be linked to smoking. However, only 15% of heavy smokers will develop lung cancer. 86% of those people will be dead within 5 years of diagnosis. I actually am shocked at how low that number is, though. That most people, fully 85% of them, could smoke a pack per day for decades and not get cancer is remarkable. It is a testament to how resilient the human body is.
So should you play the odds and smoke? There are only two games that I enjoy at the casino: Texas Holdem Poker and craps. If you're a smoker, your odds of getting cancer are the same as your opponent catching his open-ended straight draw on the river...or the same as tossing 7 and crapping out. Those things sure seem like they happen more than they do, and that's only when there is a little money on the line.