If you’ve never smoked a cigarette before, you might assume you’re safe from developing lung cancer. Unfortunately, recent statistics indicate that you can be diagnosed with the disease even if you’ve never touched a cigarette.
While smoking remains the biggest risk factor for lung cancer, rates of the disease in people who have never smoked (aka “never-smokers”) are steadily climbing.
A study published in 2017 found that the incidence of non-small cell lung cancer (NSCLC, the most common type of the disease) in never-smokers has been on the rise, increasing by 8 percent between 1990 and 1995 and by 14 percent between 2011 and 2013.
Up to 20 percent of people who die from lung cancer each year have never smoked or used any form of tobacco. So, what’s behind the increase in cases among never-smokers?
This article explores possible reasons for the uptick. We also review the specific type of lung cancer never-smokers get, who tends to develop it, and what can be done to prevent it.
Lung Cancer in Never-Smokers: Who Gets It?
Female never-smokers are more susceptible to lung cancer than males, according to the statistics. Young women who have never smoked, in particular, have more than twice the risk of developing lung cancer, compared with men who have never smoked. A study published in 2020 showed that nearly half of women diagnosed with lung cancer worldwide are never-smokers, compared with only about 15 to 20 percent of men diagnosed with lung cancer.
“There is also a higher prevalence in Asian individuals, due to a greater frequency of [certain genetic] mutations in these populations,” says Manmeet Ahluwalia, MD, chief scientific officer and chief of medical oncology for Miami Cancer Institute, part of Baptist Health South Florida.
What Type of Lung Cancer Do Never-Smokers Get?
Never-smokers who get lung cancer tend to develop adenocarcinoma, the most common form of NSCLC. This type of cancer develops from the glandular cells that produce mucus, and the tumors tend to grow on the outer parts of the lungs. Adenocarcinoma also tends to spread more slowly than other forms of cancer and has a better chance of being detected before it has spread to other organs.
It’s important to remember that smoking is still the leading cause of adenocarcinoma.
Among cigarette smokers, however, the predominant form of lung cancer tends to be squamous-cell carcinoma. This type of NSCLC develops in the epithelial cells of the airways in the center of the lung and spreads more quickly than adenocarcinoma.
Why Are Never-Smokers Getting Lung Cancer?
The explanation is complex, likely due to many factors, and is not fully understood, says Andrew Kaufman, MD, a thoracic surgeon at Mount Sinai Hospital in New York City. “We know very little about why this is occurring and why it seems to be occurring at higher rates now compared with historical time points,” he says.
Research points to some possible explanations. “Increased secondhand smoke, radon exposure, air pollution, a family history of lung cancer, and asbestos influence this trend, accounting for nearly 6,500 of the 20,000 to 40,000 yearly cases of lung cancer among never-smokers in the United States,” says Dr. Ahluwalia.
Here are some possible reasons for the increase in lung cancer cases among never-smokers.
An Increase in Never-Smokers
“The number of people who never smoked as a proportion of the general population is higher now than ever in the last 100 years because the rates of smoking have declined to about 20 percent of the adult population,” says Dr. Kaufman. “So, with fewer people having a history of smoking, there is a higher chance of diagnosing lung cancer that is not attributable to smoking.”
As the authors of a recent Nature paper note: “With smoking rates declining, [lung cancer in never-smokers] might eventually predominate lung cancer diagnoses.”
Genetic Mutations
People who have never smoked but get lung cancer often have genetic mutations in their cancer cells that contribute to cancer development. “Many never-smoking lung cancers harbor genetic mutations known as ‘driver mutations’ that cause otherwise healthy lung cells to become cancerous,” says Kaufman. “But we don’t know what causes these mutations to occur.”
Common mutations in never-smokers who develop lung cancer include changes in the EGFR, ALK, and ROS1 genes, among others. For example, Asian populations tend to have a greater frequency of EGFR mutations and ALK rearrangements, which may account for their higher rates of lung cancer in never-smokers, explains Ahluwalia.
Fortunately, there are drugs and therapies available to target many of these mutations, which can be used alone or in combination with chemotherapy. Examples include osimertinib, lazertinib, crizotinib, and many more, says Ahluwalia, who also stresses the importance of personalized medicine for lung cancer care. “These therapies have significantly improved survival and quality of life for never-smokers [with lung cancer],” he adds.
Family History
People with a family history of lung cancer have a greater risk of developing the cancer themselves. This is especially true if you have a first-degree relative (a parent or sibling) who developed lung cancer before age 50.
One review of existing studies found that the risk of lung cancer in never-smokers doubles among people who have a first-degree relative with the condition, and this risk increases further if the relative was young (under 40) when they were diagnosed — or if the person in question had multiple relatives with the condition.
More Screening
Doctors may be detecting more lung cancers in people who have never smoked because of the increased use of screening technologies. “We image people for so many things unrelated to lung cancer that we end up finding things incidentally,” says Kaufman. “Someone’s kidney stones may save their life if a spot on the lung is noticed and the appropriate diagnosis and care is followed through.”
However, screening never-smokers for lung cancer specifically is not recommended by the U.S. Preventive Services Task Force. This is because the potential benefits of early lung cancer detection don’t outweigh the possible harms in this group.
“Never-smokers with a family history or consistent exposure to occupational or environmental risks should [decide together] with their provider to assess the need for screening,” says Ahluwalia.
Secondhand and Thirdhand Smoke
Secondhand smoke — smoke breathed in from another person’s cigarette or tobacco product — accounts for about 7,000 lung cancer deaths each year in the United States.
“Recent studies have reported that secondhand smoke exposure alone increases one’s risk of lung cancer by over 20 percent, even if they never partake,” says Ahluwalia.
Researchers are also looking at the impact of “thirdhand smoke.” This is the film of nicotine and chemicals that may be left on walls, furniture, clothing, and other surfaces. These small particles can penetrate deep into surfaces, and they’ve also been found in dust samples taken from people’s homes. Current research indicates that the particles can damage human DNA in cell cultures and may raise lung cancer risk in animal studies.
Radon Exposure
Radon is a naturally occurring radioactive gas that trickles into homes from the ground. Researchers estimate radon gas exposure accounts for about 21,000 lung cancer deaths each year.
Radon exposure is the second leading cause of lung cancer but the most common cause of lung cancer in nonsmokers. Some recent studies have suggested that modern building construction practices have led to an increase in the amount of radon concentration in homes. The Environmental Protection Agency estimates that 1 in 15 homes in the United States has unsafe levels of radon.
Other Environmental Pollutants
Other environmental factors may lead to lung cancer in people who don’t smoke, such as exposure to:
Air pollution
Diesel exhaust
Asbestos
Arsenic
Arsenic compounds, such as pesticides and herbicides
X-ray and radiation technology
Inhaled chemicals such as cadmium, chromium, and coal
How Can You Lower Your Chances of Developing Lung Cancer?
Never-smokers can help lower their risk of lung cancer by avoiding secondhand smoke and exposure to radon, asbestos, arsenic, or other harmful pollutants.
“People should also ensure proper home ventilation, test for radon levels, and use protective measures in high-risk occupational settings,” says Ahluwalia. “Maintaining a healthy lifestyle with regular physical activity and a diet rich in antioxidants may further support lung health.”
Last but not least, it’s also important to seek medical care if you develop any early symptoms, because lung cancer, especially, is a disease that is most easily treated when caught early. Symptoms to look out for include:
A nagging, persistent cough
Coughing up blood
Loss of energy
Unexplained weight loss
Shortness of breath
Chest pain
“Awareness is everything. Diagnosis at an early, curable stage is critical,” says Kaufman. “Don’t hesitate to see your doctor if you develop symptoms.”
The Takeaway
Causes of lung cancer in never-smokers include exposure to secondhand smoke, radon, and other environmental pollutants; certain genetic mutations; and a family history of lung cancer.
Many therapies are available that can improve outcomes. Precision oncology and personalized medicine have also transformed the landscape of lung cancer care.
Routine screening is generally not recommended for never-smokers. However, if you have a family history of the condition or have been routinely exposed to dangerous chemicals, discuss the potential benefits of lung cancer screening with your provider.
Early detection is key to improving your outlook. See your healthcare professional right away if you develop symptoms.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
Pelosof L et al. Proportion of Never-Smoker Non-Small Cell Lung Cancer Patients at Three Diverse Institutions. Journal of the National Cancer Institute. January 28, 2017.
Stanley FK et al. Radon Exposure Is Rising Steadily Within the Modern North American Residential Environment, and Is Increasingly Uniform Across Seasons. Scientific Reports. December 3, 2019.
Dr. Tan's research has been published in multiple medical and scientific journals, including Oncologists, Cancer Cell, and Genes and Development.
A graduate of the Beijing Medical University, Tan holds an M.D. from Peking University Health Science Center and a Ph.D. from Rutgers University. Her training includes fellowships at the University of California San Francisco Cancer Research Institute and the Fox Chase Cancer Center at Temple University.
Julie Marks is a freelance writer with more than 20 years of experience covering health, lifestyle, and science topics. In addition to writing for Everyday Health, her work has been featured in WebMD, SELF, Healthline, A&E, Psych Central, Verywell Health, and more. Her goal is to compose helpful articles that readers can easily understand and use to improve their well-being. She is passionate about healthy living and delivering important medical information through her writing.
Prior to her freelance career, Marks was a supervising producer of medical programming for Ivanhoe Broadcast News. She is a Telly award winner and Freddie award finalist. When she’s not writing, she enjoys spending time with her husband and four children, traveling, and cheering on the UCF Knights.
Ana is a freelance medical copywriter, editor, and health journalist with a decade of experience in content creation. She loves to dive deep into the research and emerge with engaging and informative content everyone can understand. Her strength is combining scientific rigor with empathy and sensitivity, using conscious, people-first language without compromising accuracy.
Previously, she worked as a news editor for Medical News Today and Healthline Media. Her work as a health journalist has reached millions of readers, and her in-depth reporting has been cited in multiple peer-reviewed journals. As a medical copywriter, Ana has worked with award-winning digital agencies to implement marketing strategies for high-profile stakeholders. She’s passionate about health equity journalism, having conceived, written, and edited features that expose health disparities related to race, gender, and other social determinants of health.
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