Lung cancer is the most common cancer worldwide, with an estimated 1.8 million new cases and 1.6 million deaths in 2012 .
The identification of the factors responsible for lung cancer permits targeted efforts at prevention. The main risk factor is cigarette smoking, which accounts for approximately 90 percent of cases in men and an estimated 70 to 85 percent of cases in women . A variety of other environmental and occupational exposures, familial risk factors, dietary factors, and certain types of benign lung disease have also been associated with the development of lung cancer. The risk factors for lung cancer are discussed separately. (See "Cigarette smoking and other risk factors for lung cancer".)
The most important approach to lung cancer prevention is smoking cessation. However, even after people stop smoking, there is an increased risk of developing lung cancer for at least 30 to 40 years . The limitations of smoking cessation are emphasized by the fact that ex-smokers make up nearly 50 percent of all new lung cancer cases in developed countries.
Chemoprevention can be classified as primary, secondary, or tertiary, based upon the target population:
●Primary chemoprevention refers to preventing cancer in healthy individuals who are at high risk. This population primarily includes current and former smokers, as well as those with exposure to known carcinogens such as asbestos.