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Male with lung cancer risk factors coughing in doctor's office

Lung cancer is the second most common type of cancer among both men and women, and it is the leading cause of cancer death in the United States. According to the American Cancer Society, one in 16 men and one in 17 women will develop lung cancer during their lifetime.

What causes lung cancer?

Lung cancer forms when changes (mutations) occur in the DNA of a formerly healthy lung cell. DNA is essentially a set of instructions that tells the cell how to develop, reproduce and survive. A cellular mutation can cause the instructions to go awry, resulting in uncontrolled cell growth and proliferation. Instead of functioning normally, the abnormal cells accumulate, bind together and form cancerous tumors in the lungs.

What are the risk factors for lung cancer?

A risk factor is an attribute, behavior or exposure that may increase the likelihood of developing a certain medical condition. Through extensive research, scientists have identified several lung cancer risk factors.

Lung cancer risk factors that can be changed

Some lung cancer risk factors can be controlled with healthy lifestyle practices. These include:

Smoking tobacco

Smoking is unquestionably the leading risk factor for lung cancer. Experts believe 80-90% of lung cancer deaths are caused by smoking tobacco, which contains a toxic blend of more than 7,000 chemicals, including many carcinogens. Smoking introduces these toxins directly into the lungs.

According to the Centers for Disease Control and Prevention (CDC), cigarette smokers are 15 to 30 times more likely to develop and die from lung cancer than nonsmokers. Smoking also increases the risk of developing cancer in other parts of the body, including the throat, esophagus, stomach, colon and kidneys.

While a smoker’s lung cancer risk increases with the number of cigarettes they smoke each day and the number of years they smoke, they can reduce their risk by quitting. Individuals who want to quit smoking and improve their lung health are encouraged to see a physician for individualized guidance on smoking cessation.

Exposure to secondhand smoke

Individuals who do not smoke but frequently inhale the tobacco smoke of others have an increased risk of developing lung cancer. Researchers have confirmed that exposure to secondhand smoke is just as harmful as smoking. Therefore, by avoiding secondhand smoke, it may be possible to reduce the risk of lung cancer.

Exposure to radon

Radon is an odorless gas that occurs naturally in the soil and rock in various parts of the world. While radon is normally present in low levels outdoors, it can build up inside houses and buildings after entering through floor cracks, construction joints or foundation gaps. Prolonged radon exposure is currently recognized as the second leading cause of lung cancer in the United States.

Exposure to asbestos

A naturally occurring fibrous silicate mineral that is highly resistant to heat and corrosion, asbestos was frequently used in building materials before it was banned by the U.S. Environmental Protection Agency (EPA) in 1989 after it was conclusively linked to lung cancer. Although the government ban has reduced the risk of prolonged asbestos exposure, individuals who work in the construction, firefighting, mining, shipbuilding and military industries may still have some level of exposure.

Exposure to silica

Crystalline silica is a mineral naturally found in sand, soil and stone as well as in some man-made materials, such as bricks, concrete and mortar. The most common type of crystalline silica is quartz. When airborne silica is inhaled, such as in the form of quartz dust, it can penetrate deep into the lungs and increase the risk of lung cancer. Although quartz dust is most commonly inhaled in industrial settings, the general population may be exposed when using quartz-containing commercial products, such as certain cosmetics, cleansers and art materials.

Exposure to diesel exhaust

A fuel made from crude oil, diesel is commonly used in large engines, such as those found in ships, trains, trucks, buses, construction vehicles, farm equipment and generators. Studies suggest that heavy, long-term exposure to diesel exhaust can lead to the development of lung cancer. Although most people inhale a relatively small amount of diesel exhaust when driving on highways, those who spend a significant amount of time on or near roads and freeways, load and unload trucks, operate diesel-powered machinery or work near diesel equipment may inhale a larger amount of diesel exhaust and face higher health risks.

Using certain dietary supplements

Beta-carotene supplements have been conclusively linked to an increased risk of lung cancer, particularly in smokers. Therefore, beta-carotene supplements are not recommended for general use, especially in high doses.

Lung cancer risk factors that cannot be changed

Certain lung cancer risk factors cannot be controlled, such as:

Family history

Although lung cancer is not generally considered to be a hereditary condition, those who have a parent, sibling or child who was diagnosed with lung cancer may be at heightened risk. One possible explanation is that family members often share the same living conditions and exposures.

Prior radiation therapy

Radiation therapy delivered to the chest to treat Hodgkin lymphoma, breast cancer, a prior bout of lung cancer or another medical condition can increase the risk of developing lung cancer in the future.

Does smoking marijuana cause lung cancer?

Although scientists have conclusively linked smoking tobacco with lung cancer, they are still investigating a possible link between smoking marijuana and lung cancer. Some studies suggest that heavy, regular marijuana use may increase the risk of lung cancer, but other studies are unclear.

In addition to possibly increasing the risk of lung cancer, smoking marijuana poses many other health concerns. For example, studies suggest that it can inflame the lung’s airways, increase airway resistance, cause air to become trapped within the lungs (lung hyperinflation) and increase the risk of recurrent respiratory infections.

Does vaping cause lung cancer?

vape penGiven the relatively recent popularization of e-cigarettes, researchers do not yet fully understand their long-term effects, including a possible connection to lung cancer. With that said, many e-cigarettes contain a host of dangerous chemicals, including acetaldehyde and formaldehyde, which are known to increase the risk of lung cancer.

Is emphysema a risk factor for lung cancer?

A chronic obstructive pulmonary disease, emphysema results from long-term exposure to airborne irritants, such as tobacco smoke, marijuana smoke, chemical fumes and other forms of air pollution. When inhaled, these irritants can cause the air sacs in the lungs to become damaged and enlarged, which can lead to difficulty breathing and shortness of breath.

While emphysema is not a known risk factor for lung cancer, both emphysema and lung cancer are associated with long-term exposure to tobacco smoke and other known carcinogens. Therefore, individuals who develop emphysema as a result of tobacco use or exposure to carcinogens may be at a heightened risk for developing lung cancer.

Frequently asked questions (FAQs) about lung causes and risk factors

The following FAQs-related articles provide additional information about lung cancer causes and risk factors:

Benefit from world-class care at Moffitt Cancer Center

If you would like to learn more about lung cancer causes and risk factors, you can request an appointment with a specialist in Moffitt’s comprehensive Thoracic Oncology Program by calling 1-888-663-3488  or submitting a new patient registration form online. We do not require referrals.


Lung Cancer Statistics | How Common is Lung Cancer? | American Cancer Society
Lung Cancer Risk Factors | Smoking & Lung Cancer | American Cancer Society
What Are the Risk Factors for Lung Cancer? | CDC
What Do We Know About E-cigarettes? | American Cancer Society
American Cancer Society: Diesel Exhaust and Cancer Risk
Lung Cancer Center: Does Vaping Cause Lung Cancer?
National Cancer Institute: Asbestos Exposure and Cancer Risk
National Cancer Institute: Crystalline Silica
National Cancer Institute: Radon and Cancer