Can You Get Lung Cancer Without Smoking?

Published on: November 12, 2025

Even if you’ve never touched a cigarette, you could still be at risk for lung cancer. In fact, anyone can get lung cancer. While smoking is the leading cause of the disease, about 1 in 5 people diagnosed with lung cancer have never smoked or have smoked fewer than 100 cigarettes in their lifetime.

"A common misconception is that only people who smoke get lung cancer, which can delay diagnosis in people who do not smoke. Lung cancer in people who do not smoke is a growing global health issue," said Charu Aggarwal, MD, MPH, an American Society of Clinical Oncology (ASCO) expert and lung oncologist at Penn Medicine.

What causes lung cancer in people who don’t smoke?

People who don’t smoke usually have different risk factors for lung cancer than people who do. For people who use tobacco, being exposed to the smoke from cigarettes and other tobacco products is the main risk factor. Their risk increases with the number of cigarettes smoked per day and the number of years they have smoked. But being exposed to certain other chemicals in the air at home or at work can also increase the risk for lung cancer.

“Lung cancer in people who don’t smoke is biologically distinct from lung cancer in people who do. In people who do not smoke, the causes are more often gene changes, environmental pollution, or work-related exposures, rather than the cancer-causing agents in tobacco,” said Dr. Aggarwal.

The known risk factors of lung cancer in people who don’t smoke include:

Radon gas: Radon is a gas you can’t see or smell. It occurs naturally when soil and rocks break down. While radon disappears into the outside air, it can build up indoors by seeping into houses and other structures. Breathing it in may increase the risk of lung cancer.
Secondhand smoke: Being around people who smoke exposes you to the same cancer-causing agents that they inhale. Secondhand smoke can increase your risk of lung cancer, even if you don’t smoke yourself.
Workplace exposure: People who work around certain chemicals face increased risk for lung cancer. For example, exposure to asbestos or diesel exhaust can increase a person’s chances of getting lung cancer.
Air pollution: Cars, factories, and power plants release tiny particles into the air. Over time, these particles can damage lung cells and increase cancer risk.
Family history and inherited gene changes: Having a parent or sibling with lung cancer increases your own risk, even if they did smoke and you don’t smoke. This may be because you share similar genetics, live in similar environments, or both. Lung tumors in people who do not smoke often have changes in certain genes, such as EGFR, CHEK2, ATM, TP53, BRCA1, and APC gene mutations.
Other gene changes: As we age, changes occur in the DNA found in our genes. These are called acquired changes. Sometimes these changes happen because a person was exposed to certain chemicals. Sometimes the cause of the gene change is not known. But changes that affect certain genes can lead to abnormal cell growth and cancer. People who don’t smoke and are diagnosed with lung cancer are more likely to have one of these gene mutations: EGFR, ALK, ROS1, MET, RET, BRAF, and NTRK.

How can you lower your risk for lung cancer if you don't smoke?

Remember, no form of tobacco is safe. By not smoking, you’ve taken the biggest step to keep your lungs healthy. Staying tobacco-free is the best way to protect your health and the health of those around you. But you can also do more, such as:

Test your home for radon. Research estimates that radon is the second leading cause of lung cancer. Inexpensive test kits are available online or at hardware stores. If a test shows that your home has high levels of radon, a radon specialist can help you figure out what to do next.
Avoid secondhand smoke. This year in the U.S., more than 6,000 people are expected to be diagnosed with lung cancer caused by secondhand smoke. Try to stay away from other people’s smoke, which exposes you to dangerous cancer-causing agents.
Limit exposure to pollution. Monitor air quality in your area using apps or news reports, and limit outdoor activity when pollution is high. If you may be exposed to air pollutants at work, reduce the time you spend around them and make sure to use safety equipment.
Know your history. Talk to your family about their health history. Share that information with your doctor, especially if a close relative has had lung cancer.

What are the symptoms of lung cancer?

The symptoms of lung cancer are the same in people who don’t smoke and people who do. Usually, symptoms of lung cancer, no matter what its cause, don’t appear until the cancer is already advanced. This is why getting regular checkups and reporting symptoms is so important.

Symptoms can include:

A cough that doesn't go away
Coughing up blood
Chest pain
Hoarseness
Shortness of breath
Wheezing

Even when lung cancer does cause symptoms, many people may mistake them for other problems. Because of this, people may delay telling their doctor. People who don’t smoke are especially likely to wait because they may mistakenly think they aren’t at risk for lung cancer.

If you have symptoms that could be from lung cancer, see your doctor right away. Lung cancer can affect anyone, whether they smoke or not. If you’re concerned about your level of risk, talk to your doctor about prevention.

Learn more about lung cancer risk and prevention from the American Cancer Society:

Dr. Aggarwal is a member of ASCO’s Patient Information Advisory Committee.