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Lung cancer in nonsmokers

Thousands of nonsmokers are diagnosed with lung cancer every year. Learn what you can do to reduce your risk.

When you think of lung cancer, the next thing that comes to mind is probably smoking. And it should, according to Norman Edelman, MD, senior scientific adviser at the American Lung Association.

"Smoking is by far the biggest risk factor for lung cancer," Dr. Edelman says. About 80% of lung cancer deaths are thought to result from smoking, according to the American Cancer Society (ACS).

But lung cancer can also occur in nonsmokers. Sometimes the cause of lung cancer in nonsmokers can't be determined. But more often these cancers result from certain substances in the environment—both indoors and outdoors—that are breathed into the lungs.

Why it happens

As with all cancers, lung cancer begins when the genetic material in cells is damaged. There are several possible causes of damage.

Genetics. A family history of lung cancer may slightly raise your risk for the disease. And a small number of cases occur from random genetic mutations.

Carcinogens. Most lung cancer in nonsmokers comes from breathing cancer-causing substances in the workplace or home. The ACS and other medical experts list these common carcinogens:

  • Radon. This odorless, colorless gas is the second leading cause of lung cancer in the U.S. It rises from the soil and can enter buildings through gaps or cracks in the foundation. About 1 in 15 homes in the U.S. has excessive levels of radon and may benefit from a venting system to reduce the risk.
  • Asbestos. These naturally occurring mineral fibers have been widely used in products such as ceiling and floor tiles, pipes and brake linings. People who work directly with asbestos, in mining or manufacturing, for example, are at higher risk for lung cancer. Home remodeling can also release asbestos fibers and create a risk.
  • Other workplace substances, such as arsenic, vinyl chloride and some coal products can cause lung cancer if they are inhaled.
  • Air pollution. Smoke, vehicle exhaust, industrial emissions and haze contain small particles that can be inhaled deep into the lungs. Long-term exposure to these particles can raise the risk for lung cancer.
  • Secondhand smoke. Cigarettes affect more than the smoker—about 7,000 nonsmokers die each year from breathing someone else's smoke. According to the ACS, living with a smoker or being exposed to secondhand smoke in the workplace raises your risk for lung cancer by 20% to 30%.

Adding up the risks

Your body's immune system repairs most cell damage, whether from random genetic mutations or carcinogens. But over time, the damage that isn't repaired can add up.

Because of this, it's important for everyone to avoid carcinogens whenever they can. Dr. Edelman advises people to have their homes tested for radon and be aware of cancer-causing substances in the workplace.

You should also remember that smoking is still the major risk factor for lung cancer.

"We certainly don't want to downplay the role of smoking," Dr. Edelman says. "It's true that people who never smoked can get lung cancer, but it's still important for smokers to quit."

Reviewed 7/22/2020

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