Causes and Risk Factors of Lung Cancer

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

Lung cancer—or a malignancy that begins in the lungs—is the second most common type of cancer among men and women and the leading cause of cancer death in the United States. The American Cancer Society states that a man's lifetime risk of developing lung cancer is about 1 in 16, while a woman’s is 1 in 17.

What causes lung cancer? 

Lung cancer forms when changes (mutations) occur in the DNA of previously healthy lung cells. DNA is essentially a set of instructions that tell cells how to develop, reproduce and survive. These instructions can go haywire when cellular mutations occur, resulting in cells that rapidly divide and survive longer than they should. And instead of functioning normally, these cells accumulate, bind together and form cancerous tumors in the lungs.

Lung cancer risk factors 

A risk factor for lung cancer is anything that may increase a person’s likelihood of developing this condition. Through dedicated research, scientists have identified several lung cancer risk factors. While some of these factors, like a patient’s genetics or medical history, can’t be changed, others can be mitigated through healthy lifestyle adjustments.

Smoking tobacco

Smoking is unquestionably the No. 1 risk factor for lung cancer. Approximately 80% of all lung cancer deaths are thought to be caused by smoking. Cigarettes contain a toxic blend of more than 7,000 chemicals, including a number of carcinogens, and smoking introduces those toxins into the lungs.

According to the Centers for Disease Control and Prevention (CDC), cigarette smokers are 15 to 30 times more likely to develop lung cancer or die from the disease than people who do not smoke. Smoking also increases the risk of getting other cancers, including throat, esophagus, stomach, colon and kidney malignancies, among several others.

While a person’s lung cancer risk goes up with the number of cigarettes they smoke per day and the number of years they have smoked, their risk can go down if they are able to stop smoking. Individuals who want to quit smoking and improve their lung health are encouraged to speak with a doctor about effective quitting strategies and to receive personalized guidance.

Exposure to secondhand smoke

People who do not smoke but are frequently around those who do also have an elevated risk of lung cancer. Inhaling another person’s toxic cigarette smoke is known as secondhand smoke exposure, and it is essentially the same act as smoking a cigarette. Staying away from people while they smoke can help reduce secondhand smoke exposure and lower the risk of lung cancer.

Radon exposure

Radon is an odorless, naturally occurring gas that is found in soil and rocks around the world. It is normally present in low levels outdoors, but can collect in large amounts inside houses and buildings through floor cracks, construction joints and gaps in foundations. Prolonged radon exposure is currently recognized as the second leading cause of lung cancer.

Asbestos exposure

Inhaling asbestos over the course of several years may increase the risk of lung cancer. Asbestos is a naturally occurring group of minerals that was once frequently used in various building materials for its resistance to heat and corrosion. While government regulations established in the 1980s have reduced the risk of prolonged asbestos exposure, workers in the construction, firefighting, mining, shipbuilding and military industries may still have some level of exposure. 

Silica exposure

Crystalline silica is a mineral that’s naturally found in sand, soil and stones, as well as in man-made materials such as bricks, concrete and mortar. The most common type of crystalline silica is quartz. When airborne silica (for example, quartz dust) is inhaled, it can penetrate deep into the lungs and lead to the development of lung cancer. Although quartz dust is most commonly inhaled in industrial settings, the general population may still be exposed to it when using commercial products containing quartz, including certain cosmetics, cleansers and art materials.

Exposure to diesel exhaust

Diesel—a type of fuel made from crude oil—is commonly used in large engines, such as those in ships, trains, trucks, buses, construction vehicles, farm equipment and generators. Many studies suggest that heavy, long-term exposure to diesel exhaust can lead to the development of lung cancer. Although many people inhale relatively small amounts of diesel exhaust when driving on highways, the individuals who are most at risk include those who are exposed to it on a daily basis at work.

Family history

Lung cancer isn’t generally considered to be a hereditary condition, but a person may have an increased risk of disease if their parent, sibling or child has lung cancer. This may possibly be attributed to families often living in similar environments and being exposed to the same substances.

Previous radiation therapy

Having a history of receiving radiation therapy to the chest to treat a previous diagnosis of Hodgkin disease, breast cancer, a separate case of lung cancer or another condition can increase the risk of developing lung cancer in the future.

Dietary supplements

There is still much to understand about the link between diet and lung malignancies, but taking beta carotene supplements has been shown to increase the likelihood of developing lung cancer, particularly among smokers. Eating a diet high in fruits and vegetables may decrease lung cancer risk, but this connection is still being studied.

Does vaping cause lung cancer?

Although it’s well known that smoking tobacco can lead to the development of lung cancer, many people question whether vaping can cause lung cancer. Given the relatively recent popularization of e-cigarettes, no one yet knows what long-term effects they may cause, and researchers are still working to determine whether vaping can increase a person’s risk of developing lung cancer. With that being said, many e-cigarettes contain dangerous chemicals that have previously been associated with a higher risk of lung cancer, including formaldehyde.

Common lung cancer causes and risk factor FAQs

Do you still have questions about lung cancer causes or risk factors? If so, browse some of the most frequently asked questions on this topic: 

Lung cancer diagnosis and treatment at Moffitt 

At Moffitt Cancer Center—Florida’s No. 1 cancer hospital—we help each patient evaluate their individual lung cancer risk factors and determine next steps. For instance, long-time smokers may benefit from our lung cancer screening program, which is among the best in the nation. In fact, Moffitt has been named a Screening Center of Excellence by the Lung Cancer Alliance.

To make an appointment with a Moffitt oncologist with or without a referral, complete a new patient registration form online or call 1-888-663-3488. You’ll be put in touch with a Moffitt professional who can address your specific needs as soon as possible. 


American Cancer Society: Diesel Exhaust and Cancer Risk
American Cancer Society: What Do We Know About E-cigarettes?
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