Risk Factors

A risk factor is a behavior or characteristic that increases someone's chance of developing a disease.

Smoking is the number one risk factor for lung cancer. Tobacco smoke contains more than 40 cancer-causing chemicals. The risk of developing lung cancer from tobacco use is related to the age at which smoking began, how many years the person has smoked, the number of cigarettes or packs per day that a smoker uses, and how deeply the smoker inhales.

Radon. Radon is an invisible, odorless gas that occurs naturally in the soil. Indoor radon is the second leading cause of lung cancer after smoking.

Asbestos. Asbestos fibers occur naturally and are used in some forms of insulation and in the shipping industry. When air born asbestos fibers are inhaled, they damage lung tissue. Asbestos increases the risk of lung cancer four to five times. Exposure to asbestos combined with smoking increases the risk 100 times.

Pollution. Researchers continue to explore the links between lung cancer and exposure to certain types of air pollutants.

Lung Diseases. Some lung diseases, like tuberculosis, increase the likelihood of developing lung cancer, especially in regions of the lung that are already scarred. A person who already has been treated for lung cancer is more likely to develop a second lung tumor than someone who has never had lung cancer.

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This article was reviewed and updated June 2007.