Cigarette Smoking, Lung Cancer, and Statistics

It's well-known that cigarette smoking increases risk for lung cancer.  Cigarette smoking is responsible for approximately 90% of all cases of lung cancer.  The risk of a current smoker with a 40 pack-year smoking history is about 20 times that of someone who has never smoked. 

Several other factors increase the risk for lung cancer.  The combination of smoking history and asbestos exposure escalates the risk to as high as 50 to 90 times that of a never-smoker.  The presence of airway obstruction on pulmonary function testing increases the risk to a four- to sixfold.




Sigmund Freud, whose doctor assisted his suicide because of cancer caused by smoking



The most effective method for reducing current smokers' risk is to quit.  After a current smoker quits smoking, the risk for lung cancer falls steadily for about 15 years before the risk levels off.  The risk, however, remains twice that of a never-smoker.  In other words, a 15-year smoking cessation reduces the risk from 20 to 2.