Lung Cancer Is Rising Among Nonsmokers

Many people know tobacco smoking significantly increases the risk of lung cancer. Lung cancer in people who have never smoked is an important and increasingly recognized public health concern. Researchers are investigating how its incidence and causes vary across populations.

The CDC estimates that approximately 10%–20% of lung cancer cases in the United States occur in people who never smoked or smoked fewer than 100 cigarettes over their lifetime. Worldwide, this occurs in 25% of lung cancer cases.

We now treat lung cancer in nonsmokers as a distinct disease. Radon exposure is the number one cause of lung cancer in people who have never smoked. Secondhand smoke, air pollution, and other carcinogen exposure are other major contributors to lung cancer in never smokers.

Nonsmokers can protect their lung health by avoiding air pollution and other hazards, such as radon and chemical exposure at home or work. Meanwhile, early detection and advances in treatment, such as targeted therapies and checkpoint inhibitors, are helping more people live longer with the disease.

How Widespread Is Lung Cancer in Nonsmokers?

Lung cancer is the leading cause of cancer death in men and women in the United States. More people die annually of lung cancer than of the next deadliest cancers, breast, ovarian, colorectal, and pancreatic cancer, combined.

Approximately 25% is a figure often cited for lung cancer in never-smokers globally. In the United States, the CDC estimates about 10%–20%, or approximately 20,000–40,000 cases annually.

Two-thirds of cases are diagnosed in women, with numbers higher among women of East Asian ancestry. More young people than in the past are being diagnosed. Nonsmokers with lung cancer may not be considered at risk, and their symptoms can be mistaken for other illnesses.

Nonsmokers often have a different type of lung cancer than smokers. More smokers than nonsmokers have small cell lung cancer. A type of non-small cell lung cancer called adenocarcinoma is most often diagnosed in nonsmokers.

Researchers and physicians worry that lack of awareness about lung cancer in nonsmokers may delay diagnosis and treatment. Lung cancer screening with a painless low-dose CT scan is not common and is covered by some public and private insurance only for people with smoking histories who are 50 or older.

“Lung cancer is often diagnosed at a later stage, when it is harder to treat. Even people who never smoked should be aware of the risk factors and talk to their physicians about concerns or symptoms.”

Sharad Chandrika, MD, Interventional Pulmonologist at Catholic Health

What Are the Causes of Lung Cancer in Nonsmokers?

No one is exactly sure why more nonsmokers are getting lung cancer, but experts say several causes contribute. They fall into three general categories:

Environmental Exposures

Radon is the leading cause of lung cancer among nonsmokers. It is a colorless, odorless radioactive gas that can build up indoors. Test kits can detect it so you can take steps to lower its concentration.
Air pollution — Air pollution may contribute to lung cancer, particularly for people who live in heavily polluted areas or are continuously exposed to secondhand smoke.
Living with a tobacco smoker — Regular exposure to tobacco smoke from someone else can increase the risk of a nonsmoker getting lung cancer.
Wood-burning stoves and fireplaces — Smoke from poorly ventilated stoves and fireplaces has been linked to lung cancer in some cases.

Family and Medical History

A family history of lung cancer, particularly in a first-degree relative such as a parent, sibling, or child. Risk is also high for people with two or more relatives who had lung cancer.
Personal history of certain lung diseases, such as COPD or pulmonary fibrosis.
Having had radiation therapy to the chest, such as for breast cancer or lymphoma treatment.
HIV infection: People living with HIV are at an increased risk for lung cancer, with some studies estimating the risk to be 1.5 to 4-fold higher compared with the general population.

Occupational Hazards

Asbestos exposure is a risk factor. Asbestos use has been restricted but not banned in the U.S. Exposure most often occurs in construction, shipbuilding, and insulation services.
Other chemical exposures that carry a risk include arsenic, diesel exhaust, silica, chromium, and nickel.

“A combination of genetic predisposition to lung cancer combined with environmental risks may account for the rise in cancer among nonsmokers,” said Dr. Chandrika. “This is an area of active research as we try to find the causes, improve treatment and extend lives.”

Can a Genetic Test Determine if I Am at Risk for Lung Cancer?

Today, the answer is generally no. Researchers find certain gene mutations more often in nonsmokers diagnosed with lung cancer than in current or former smokers. However, testing usually happens after diagnosis.

Also, gene changes found in patients with non-small cell lung cancer appear to be caused by other factors — radon or pollution, for example — and are not inherited.

What we know about genetic mutations has led to new treatments that extend patients' lives. Those treatments include drugs that target the gene mutation causing the cancer, immunotherapy, antibodies, and drugs that slow the disease's progress.

“We know more than ever about lung cancer, and we still have a lot to learn,” said Dr. Chandrika. "Some questions we have are whether genetic factors alone make someone more likely to develop lung cancer or whether genetics in combination with other things, such as exposure to air pollution, makes someone at higher risk.”

What Can I Do to Try to Prevent Lung Cancer?

The first thing is not to smoke tobacco, and if you do, quit. Smoking remains the single largest risk factor and causes the majority of lung cancer cases. Ask your physician if your smoking history and age make you a candidate for lung cancer screening with a painless and quick low-dose CT scan.

Other ways to help prevent lung cancer include:

Talk to Your Physician About Your Family Medical History

Having close relatives — parents, siblings, or children — with lung cancer may increase your risk. You may also have a higher risk of lung cancer if relatives were diagnosed before 50. You may want to ask about genetic counseling if you have a family history of related cancers, such as breast cancer, colorectal cancer, and melanoma.

Test Your Home for Radon

About 1 in 15 U.S. homes has radon. You can buy test kits at hardware stores or online. The instructions tell you where and how to set up the test, and where to send it for analysis. It is recommended to test every few years, even after negative tests.

If the test finds a potentially hazardous radon concentration, you can take steps to lower it to safer levels.

Avoid the Outdoors When Pollution Levels Are High

Wildfire smoke in recent years has put us on alert about dangerous pollution. Don't wait until the sky looks yellow or gray. Check daily weather and pollution reports so you know when levels exceed what most people consider safe. On those days, avoid outdoor exercise and keep windows and doors shut.

Home air filters and purifiers monitor and eliminate the small, invisible particles that can damage lungs over time. Particles may come from inside, such as cooking, or from outside, including wildfires, pollen, factories, and other pollution sources.

What are Symptoms of Lung Cancer?

Lung cancer is often symptomless until it has advanced. Lung cancer symptoms can be mistaken for other possible causes, like pneumonia or bronchitis, in nonsmokers.

See a physician if any of these symptoms last a few weeks or worsen over time:

Bronchitis or pneumonia that recur
Chest pain
Cough that persists or coughing up blood
Fatigue
Hoarseness

Comprehensive Lung Cancer Services on Long Island

Catholic Health’s multidisciplinary team of interventional pulmonologists, medical and radiation oncologists, and thoracic surgeons treat all types of lung cancer, even the most advanced. Learn more about our lung cancer services, including screening, diagnosis, treatment, and follow-up care.

Call 866-MY-LI-DOC (866-695-4362) to find a Catholic Health physician near you.

FAQ/People Also Ask

Should I wear an N95 mask outside to prevent lung cancer?

An N95 mask worn outdoors in polluted air can help filter particles that can harm lung tissue. Physicians recommend staying inside when pollution levels are high.

What causes radon in homes?

Radon is a radioactive gas caused by the natural breakdown of uranium in soil. It can seep in through cracks in foundations, gaps around pipes and joints, sump pumps and floor drains, and unfinished crawl spaces and dirt floors. If your tests show unsafe levels, you can take steps to reduce the risk.

Does having asthma increase the risk of lung cancer?

Yes, having severe or poorly controlled asthma can elevate your risk of lung cancer. That’s why it’s important to see a physician to control asthma and recognize any changes in your lung health.

October 22, 2026

What can we help you find?