Lung Cancer

A risk factor for lung cancer is something that increases your chance of getting this cancer. Having one or more of these risk factors can make it more likely that you will get lung cancer. But it doesn't mean that you will definitely get it. And many people who get lung cancer don't have any of these risk factors.

Smoking

About 85 out of 100 lung cancers are related to cigarette smoking.^{Reference 4} Smoking cigars or a pipe may also increase your risk for lung cancer.

Your risk of getting lung cancer increases:

• The longer you smoke.
• The more cigarettes you smoke each day.

Quitting smoking lowers your risk for getting cancer, and your risk keeps going down as long as you don't smoke. Even cutting down how much you smoke may reduce your risk (but not as much as quitting completely).

If you live with a smoker, you have a higher risk for lung cancer compared with a person who lives in a nonsmoking environment.

For more information, see the topic Reference Quitting Smoking.

Other risks

Exposure to some substances may increase your risk for lung cancer, including:

• Marijuana. Smoking one marijuana cigarette, or a joint, may affect the lungs as much as smoking a pack of cigarettes.^{Reference 5}
• Certain chemicals. These include arsenic and Reference asbestos.
• Radiation. This includes exposure from your work place, medical tests, or from the environment (such as radioactive dust).
• Radon gas. This includes exposure from your home or work place.
• Air pollution. Living where the air is very polluted can increase your risk for lung cancer.

Some gene changes (mutations) can increase the risk of getting lung cancer. These gene changes mostly occur as a person gets older.

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