What Causes Lung Cancer?
Anyone can get lung cancer. Lung cancer happens when cells in the lung mutate or change. Various factors can cause this mutation (a permanent change in the DNA sequence of a gene) to happen. Most often, this change in lung cells happens when people breathe in dangerous, toxic substances. Even if you were exposed to these substances many years ago, you are still at risk for lung cancer. Talk to your doctor if you have been exposed to any of the substances listed below and take steps to reduce your risk and protect your lungs.
Smoking is the number one cause of lung cancer. It causes about 90 percent of lung cancer cases. Tobacco smoke contains many chemicals that are known to cause lung cancer. If you still smoke, quitting smoking is the single best thing you can do for your lung health.
Smokers are not the only ones affected by cigarette smoke. If you are a former smoker, your risk is decreased, but has not gone away completely—you can still get lung cancer. Nonsmokers also can be affected by smoking. Breathing in secondhand smoke puts you at risk for lung cancer or other illnesses.
Radon exposure is the second-leading cause of lung cancer. Radon is a colorless, odorless radioactive gas that exists naturally in soil. It comes up through the soil and enters buildings through small gaps and cracks. One out of every 15 homes in the U.S. is subject to radon exposure. Exposure to radon combined with cigarette smoking seriously increases your lung cancer risk.
Exposure to certain hazardous chemicals poses a lung cancer risk. Working with materials such as asbestos, uranium, arsenic, cadmium, chromium, nickel and some petroleum products is especially dangerous. If you think you may be breathing in hazardous chemicals at your job, talk to your employer and your doctor to find out to protect yourself.
Particle pollution refers to a mix of very tiny solid and liquid particles that are in the air we breathe. Evidence shows that particle pollution—like that coming from that exhaust smoke—increases the risk of lung cancer.
Genetic factors also may play a role in one's chances of developing lung cancer. A family history of lung cancer may mean you are at a higher risk of getting the disease. If others in your family have or ever had lung cancer, it's important to mention this to your doctor.
Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.
Page last updated: November 17, 2022