Non-small cell lung cancer (NSCLC) is a type of cancer that begins in the tissues of the lungs. About 80-85% of all lung cancer cases in the United States are classified as NSCLC.
NSCLC occurs when the cells that line the surface of the lung airways change and mutate. When these abnormal cells rapidly divide and multiply, they lead to cancer. The most common cause of NSCLC is smoking, with about 90% of lung cancer cases being related to tobacco smoke exposure.
It is possible to be diagnosed with NSCLC if you have never smoked. Other potential causes include exposure to radon, asbestos, and certain chemicals.
The most common cause of non-small cell lung cancer is smoking tobacco. Smoking damages the cells lining the airways. Once damaged, the cells grow and multiply at an out-of-control rate.
Your risk of NSCLC is affected by your smoking habits. The more cigarettes you smoke daily and the longer you have smoked, the greater your risk is for NSCLC. Smoking cigars or a pipe also increases your risk of NSCLC.
It is possible to develop NSCLC after you quit smoking. However, the risk of lung cancer decreases the longer you have not smoked.
Even if you don’t smoke, smoke can still cause lung cancer. Exposure to secondhand smoke—breathing in the smoke from someone else’s tobacco product—can lead to lung cancer. Secondhand smoke is believed to have nearly 70 cancer-causing chemicals in it.
Radon exposure is the second most common cause of lung cancer in the U.S.—the number one cause among people who don’t smoke. Radon is a naturally occurring gas found in soil and rocks. When uranium in the soil breaks down, it produces the radioactive gas known as radon.
Most people are exposed to very low levels of radon outdoors. Radon can become dangerous when it is concentrated indoors in the home or workplace. This may occur in a room closest to the soil, like a basement. Consider having your home tested for radon to learn if you are at risk.
Some types of cancers are hereditary or genetic. This means that certain gene mutations that increase the risk of cancer can be passed from parents to children. Some gene mutations may increase the risk of NSCLC.
Mutations in the following genes may increase your risk of NSCLC:
- CHEK2
- ATM
- TP53
- BRCA1
- EGFR
- APC
- PALB2
Smoking increases the odds of a gene mutation leading to lung cancer. People who have lung cancer and a known gene mutation may benefit from a type of cancer treatment called targeted therapy, which uses drugs to identify and kill specific cancer cells.
Some people are more likely to develop NSCLC than others. The following factors may affect your NSCLC risk:
- Age: Older people are more likely to be diagnosed with NSCLC than younger people. This is likely because older people have been exposed to smoking or other chemicals for longer.
- Sex: In the past, researchers believed that lung cancer was more common in people assigned male at birth than those assigned female at birth, but this is no longer the case. People assigned female at birth are just as likely or even more likely to be diagnosed with lung cancer. It is possible that those assigned female at birth were underrepresented in previous studies, and researchers did not get a complete picture of their risk.
- Ethnicity: Research shows that people assigned male at birth who are non-Hispanic Black have the highest rates of lung cancer diagnosis and death. However, due to healthcare disparities, Black individuals are 15% less likely to receive an early lung cancer diagnosis.
Smoking is the leading cause of NSCLC in the U.S. Other factors that may increase your risk of NSCLC include asbestos or chemical exposure.
Exposure to Asbestos
Asbestos is a natural mineral often found in wall insulation and vinyl tiles. It is a known carcinogen (cancer-causing substance), and inhaling asbestos increases the risk of lung cancer.
People who work in mines, mills, textile plants, shipyards, and any area with insulation are at risk of being exposed to asbestos. Researchers are uncertain how much asbestos exposure contributes to lung cancer risk.
Chemical Exposures
Exposure to certain chemicals causes lung damage and may increase the risk of cancer. Some people may be exposed to harmful chemicals at work. Inhaling arsenic, beryllium, cadmium, silica, vinyl chloride, and coal increases the risk of lung cancer.
The U.S. government requires workplaces to provide protective gear and equipment to any workers handling harmful chemicals.
Family History
People with a family history of NSCLC are at an increased risk of being diagnosed themselves. Having a parent or sibling with NSCLC raises your risk. Researchers are uncertain if this is due to genetics or similar lifestyle factors, such as living in a house with tobacco smoke.
History of Radiation
People who have received radiation therapy to the chest area may be at higher risk for lung cancer. Chest radiation therapy is often recommended for people with breast cancer and Hodgkin lymphoma. Radiation exposure causes cell damage and increases the risk of cancer. The risk is higher for people who also have a history of smoking.
Air Pollution
Living in an area with high levels of air pollution may slightly increase the risk of lung cancer. It’s estimated that about 1-2% of lung cancer deaths are due to outdoor air pollution. Factors like diesel exhaust from vehicles contribute to air pollution.
Dietary Supplements
People who smoke heavily should avoid beta-carotene supplements. These supplements have been found to increase the risk of lung cancer among people who smoke at least one pack of cigarettes a day.
Beta-carotene supplements have also been associated with higher lung cancer mortality among people who smoke.
Non-small cell lung cancer (NSCLC) is a type of lung cancer that begins in the cells lining the lung airways. It is the most common type of lung cancer in the U.S. The leading cause of NSCLC is smoking tobacco products like cigarettes, cigars, and pipes. Other possible causes include exposure to radon and secondhand smoke.
Risk factors for NSCLC include exposure to asbestos, certain chemicals, radiation, and air pollution. Having a family history of NSCLC also increases the risk. People who smoke heavily should avoid beta-carotene supplements, as the combination can increase lung cancer risk.