The whole smoking-cancer thing is suspect. For instance, the Japanese, who smoke far more than Americans on average, have a much lower incidence of lung cancer.
Personally, once again, I'm inclined to think this is nutrition/dietary deficiency related. Possibly Vit D.
The same is true in France where they smoke stronger tobacco and mostly unfiltered cigarettes.
That's nice. I was sort of sold on the thing when my chain-smoking sister died horribly at the age of 52. I've seen more deaths than I have any to right to have seen, and nothing equaled that. Tobacco causes cancer, and it causes bad cancer.
"Personally...I'm inclined to this this nutrition/dietary deficiency related."
While interesting work on Vitamin D indicates it might be related to winter depression and that 1,000 IU rather than 400 IU might be an appropriate usage, I think there are other more likely nutrients for smoking.
Smoking destroys Vitamin C, about 25 mg for each cigarette. Thus a person smoking a pack a day should take a 500 mg. Vitamin C tablet for each pack of cigarettes smoked. An orange only has 60 mg. of C. In addition it wouldn't hurt to take an additional 500 mg. for air pollution and general needs. C is eliminated or used in 4 to 5 hours, so spreading the use into 4 doses at 5 or 6 hour intervals is best.
The Japanese consume lots of seaweed or kelp in their diet which is very high in trace minerals. Taking kelp tablets, using sea salt (which is 40% mineral salts other than sodium), or a good trace mineral formula might substitute. Nature Plus(R) has a good trace mineral tablet.
Vitamin A is very good for protection of mucuous membranes. So eating raw fruits and vegetables is good. Unfortunately, chemical fertilizers may reduce or eliminate the amount of A in produce. Eating organic or taking an A & D capsule could suffice.