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Lung cancer: Causes and symptoms

Almost all cases of lung cancer are linked to first- or secondhand cigarette smoke. Avoiding it is your best protection against this cancer.

Lung cancer is the leading cause of cancer death in American men and women. Tragically, many of these cancers could have been prevented.

To reduce your chances of developing lung cancer, avoid every risk factor you can.

The causes

The National Cancer Institute lists the following known causes of lung cancer.

Smoking. The best protection against lung cancer is not smoking and avoiding people who do, according to the American Cancer Society (ACS). The more smoke you're exposed to, the greater your risk for lung cancer. Your total exposure depends on the age when you started smoking, how many years you've smoked, how many packs a day you've smoked, how deeply you inhale when you smoke and how much time you've spent in places where others were smoking.

Remember, it's not just cigarettes that increase the risk of lung cancer. Smoking cigars or pipes also raises your risk for lung cancer—even if you don't inhale. Again, more exposure equals more risk.

Radon. This radioactive gas is found in soil and rocks. It can build up to dangerous levels in mines and in some homes because of cracks and gaps in floors, joints and walls. Radon has no odor, taste or smell, but at high levels it can damage the lungs and lead to lung cancer. Kits that can measure the radon levels in your home are sold at most hardware stores.

Asbestos. When people inhale asbestos particles, the particles get stuck in the lungs and damage lung cells, sometimes leading to cancer. Asbestos was once used widely in home construction and the shipbuilding and automotive industries. Regulations and awareness have vastly reduced its use. People who work around asbestos, especially auto mechanics, demolition crews and firefighters, should follow safety procedures closely to make sure they don't breathe in asbestos particles.

Pollution. Some research has shown links between air pollution and lung cancer, especially pollution that comes from burning fossil fuels, such as diesel.

A small number of people develop lung cancer despite having none of these risk factors. Research on causes and prevention is ongoing.


There are several possible warning signs of lung cancer, but the symptoms could also be caused by something else. The only way to find the true cause of your symptoms is to see your doctor.

According to the ACS, warning signs of lung cancer include:

  • A cough that does not go away.
  • Chest pain, especially with deep breaths.
  • Hoarseness.
  • Weight loss and loss of appetite.
  • Bloody or rust-colored sputum (spit or phlegm).
  • Shortness of breath.
  • Unusual wheezing.
  • Recurring infections such as bronchitis and pneumonia.
If you have any of these symptoms, talk to your doctor right away.

Reviewed 9/12/2022

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