Risk factors

A number of factors may increase your risk of lung cancer. Some risk factors can be controlled, for instance, by quitting smoking. And other factors can't be controlled, such as your family history.

Risk factors for lung cancer include:

• Smoking. Your risk of lung cancer increases with the number of cigarettes you smoke each day and the number of years you have smoked. Quitting at any age can significantly lower your risk of developing lung cancer.
• Exposure to secondhand smoke. Even if you don't smoke, your risk of lung cancer increases if you're exposed to secondhand smoke.
• Previous radiation therapy. If you've undergone radiation therapy to the chest for another type of cancer, you may have an increased risk of developing lung cancer.
• Exposure to radon gas. Radon is produced by the natural breakdown of uranium in soil, rock and water that eventually becomes part of the air you breathe. Unsafe levels of radon can accumulate in any building, including homes.
• Exposure to asbestos and other carcinogens. Workplace exposure to asbestos and other substances known to cause cancer — such as arsenic, chromium and nickel — can increase your risk of developing lung cancer, especially if you're a smoker.
• Family history of lung cancer. People with a parent, sibling or child with lung cancer have an increased risk of the disease.