I quit 10 years ago. I'm pro smoker all the way. My dad died from smoking Camels. Still, I'm all for it if you like it. This is just silly ...
No one's ever died from smoking. Would be banned overnight if that were true.
With literally thousands of carcinogens in our enviroment, the ones that actually start a cancer is impossible to determine. You'd have to eliminate everything else then expose someone to tobacco smoke and see if they get cancer to say with certainty, smoking causes cancer. Lots of of things cause cancer. Flame retardants in our clothes and furniture are huge causes as well. Lot of our food cause cancers as well. Tobacco use is 1 risk factor among thousands of others.
For 'smoking causes cancer' to be true, every smoker would have to get cancer. In fact according to the CDC itself, only about 40% of smokers develop lung cancer. And whether it was the smoking, or some other combination of things that caused it can't be determined.