
@james 139
Nonsense. Carcinogens damage DNA; enough damage to your DNA and you start developing cancer. Go look up the two-hit hypothesis. (Actually, here, I saved you the trouble http://www.nature.com/milestones/milecancer/full/milecancer09.html ) What your DNA is like to begin with has virtually nothing to do with it with such potent carcinogens as are contained in cigarette smoke and delivered to your lungs.
The vast majority of people who develop lung cancer would not have developed that cancer if they had never smoked. Hard fact. Ten percent of smokers will develop lung cancer. Also hard fact.
Just because smoking does not cause cancer in every smoker does not mean it did not cause cancers in the vast majority of those smokers who do develop lung cancer.