Table of ContentsView AllTable of ContentsHow Common Is This?Who Is at Risk?Role of GeneticsPossible CausesSymptomsPrevention
Table of ContentsView All
View All
Table of Contents
How Common Is This?
Who Is at Risk?
Role of Genetics
Possible Causes
Symptoms
Prevention
The reason why lung cancer is increasing in non-smokers and never-smokers isn’t entirely clear. Research suggests that some people may have agenetic predispositionforlung cancerthat makes them vulnerable to environmentalcarcinogens(like air pollution, radon, asbestos, and secondhand smoke) that other people may be more resistant to.Young femalesand Asian people who have never smoked are especially vulnerable.
Because lung cancer is largely regarded as a “smoker’s disease,” non-smokers may miss the signs of the disease until it is advanced and has begun to spread. This is why it is important to recognize thesigns of lung cancerwhether you smoke heavily or have never touched a cigarette in your life.
Verywell / Luyi Wang
How Common Is Lung Cancer in Never-Smokers?
In recent decades, the rate of lung cancer among never-smokers (as opposed tonon-smokerswho may have smoked at one time) has risen dramatically.
Although tobacco smoking accounts for the vast majority of lung cancer cases, lung cancer among never-smokers is today the fifth most common cause of cancer-related deaths worldwide, according to a 2023 study published in theNational Review of Clinical Oncology.
In 2023, over 20,000 lung cancer deaths were reported among never-smokers in the U.S.,accounting for just under one-fifth of all cancer deaths for that year.
Statistically speaking, this makes lung cancer among never-smokers the eighth leading cause of cancer-related deaths in the U.S. Globally, it is the fifth most common cause of cancer-related deaths.
All told, between 10% to 15% of lung cancer cases in the United States occur in never-smokers, with rates expected to increase.
Who Is at Risk of Lung Cancer Among Never-Smokers?
Studies have shown that two groups of never-smokers are especially vulnerable to lung cancer: females and Asian people.
Statistically, female never-smokers are more than twice as likely as male never-smokers to get lung cancer. In total, around two-thirds of all cases involve women. This is despite the fact that U.S. men represent over 80% of lung cancer cases overall.
As with smokers, lung cancer among never-smokers tends to affect people over 60, albeit slightly earlier than either smokers or former smokers.
Never-smokers also differ in that they almost exclusively develop a type of cancer called lungadenocarcinoma. Adenocarcinoma is a typically slow-growingnon-small cell lung cancer (NSCLC)that affects the lining of the small airways (calledbronchioles).
Genetics and Risk of Lung Cancer in Never-Smokers
Although lung cancer is strongly associated with cigarette smoking, only around 15% of smokers end up getting the disease.This suggests that other factors contribute to the risk of cancer, both in smokers and non-smokers.
While environmental factors play a large role in this—causinginflammationandDNA damagethat causes cells to mutate—certaingenetic factorsmay make it easier for these changes to occur.
There also appear to be differences in how cancer-causing mutations develop.
With never-smokers, many of these mutations may already be present at birth. As such, fewer acquired mutations may be needed for cells to turn malignant.
This may explain in part why never-smokers tend to get lung cancer at an earlier age than smokers.
Possible Causes for Lung Cancer in Never-Smokers
As with other types of cancer, lung cancer may develop for no apparent reason. In theory, cancerous mutations may develop spontaneously in someone who is genetically predisposed to the disease.
However, lung cancer is generally thought to involve some sort of environmental “trigger” that turns an overwisebenigngrowth cancerous.
The American Cancer Society notes three possible causes among never-smokers:
Radon Gas
Radon gasis an invisible, odorless gas that can accumulate in homes built to soil containing even modest deposits of uranium. Exposure to radon gas is considered one of the leading causes of cancer among never-smokers, accounting for around 21,000 lung cancer deaths in the United States each year.
Secondhand Smoke
Secondhand smokeis the tobacco smoke you inhale from another person’s cigarette or cigar. It is estimated that over 7,000 lung cancer deaths occur in the U.S. due to secondhand smoke.
It is also possible to get exposed tothirdhand smoke. This is the invisible film ofnicotineand other chemicals left on surfaces, clothing, and furniture that you can touch and introduce into your body. Children who crawl on contaminated floors and carpets are especially vulnerable.
Occupational Exposure
There are many carcinogenic (cancer-causing) agents used in industrial and manufacturing industries that can be inhaled and increase the risk of lung cancer. These include solvents, toxins, pesticides, and heavy metals like:
People who work in construction (including masonry, painting, and sand-blasting), coal/coke plants, or ceramics, rubber, or glass manufacturing are especially vulnerable. Traffic police and long-distance drivers are at high risk of exposure to air pollution and car fumes.
Ionizing radiation exposure can occur with fracking, nuclear power plants, and uranium processing facilities, but stringent safety measures usually minimize the risk.
Lung Cancer and Cooking GasOne possible factor contributing to lung cancer in Asian females is cooking oil fumes. The high temperatures used for stir-frying in Chinese cooking can oxidize and aerosolize the oil. Studies have shown that these inhaled fumes can progressively damage the lungs, doubling the risk of lung cancer in non-smoking females.
Lung Cancer and Cooking Gas
One possible factor contributing to lung cancer in Asian females is cooking oil fumes. The high temperatures used for stir-frying in Chinese cooking can oxidize and aerosolize the oil. Studies have shown that these inhaled fumes can progressively damage the lungs, doubling the risk of lung cancer in non-smoking females.
Signs of Lung Cancer in Never-Smokers
To this end, you should be aware of the signs and symptoms of lung cancer, particularly if you have a family history of the disease.
These include:
Other tests likesputum cytologyorendobronchial ultrasoundcan be performed if imaging studies are negative or inconclusive.
How to Prevent Lung Cancer If You Don’t Smoke
Lung cancer can affect never-smokers as well as smokers and former smokers. To reduce your risk and the risk of others in your family who don’t smoke:
Summary
Between 10% and 15% of lung cancer cases in the United States involve people who never smoked. Of the roughly 125,000 people who die each year from lung cancer, never-smokers account for around 20,000 of these deaths. Females and Asian people are at greatest risk.
The cause of lung cancer in never-smokers is poorly understood, but genetics is thought to play a part. Among the most common causes in never-smokers are radon gas in the home, secondhand smoke, and occupational exposure to carcinogens like diesel fume, asbestos, and vinyl chloride.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Kusneirczyk P.Genetic differences between smokers and never-smokers with lung cancer.Front Immunol.2023;14:1063716. doi:10.3389/fimmu.2023.1063716LoPiccolo J, Gusev A, Christiani DC, Janne PA.Lung cancer in patients who have never smoked — an emerging disease.Nat Rev Clin Oncol. 2024 Feb;21(2):121–146. doi:10.1038/s41571-023-00844-0American Cancer Society.Special section: lung cancer.Pelosof L, Ahn C, Goa A, et al.Proportion of never-smoker non-small cell lung cancer patients at three diverse institutions.J Natl Cancer Inst.2017 Jan 28;109(7):djw295. doi:10.1093/jnci/djw295Yale Medicine.Non-small celll lung cancer.American Cancer Society.Lung cancer risks for people who don’t smoke.Centers for Disease Control and Prevention.Protect yourself and your family from radon.Centers for Disease Control and Prevention.Health effects of secondhand smoke.Yale Medicine.Lung cancer in non-smokers.Shankar A, Dubey A, Saini D, et al.Environmental and occupational determinants of lung cancer.Transl Lung Cancer Res. 2019 May;8(Suppl 1):S31-S49. doi:10.21037/tlcr.2019.03.05Xue Y, Jiang Y, Jin S, Lin Y.Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis.Onco Targets Ther.2016;9:2987–2992. doi:10.2147/OTT.S100949American Lung Association.How is lung cancer diagnosed?Centers for Disease Control and Prevention.Lung cancer among people who never smoked.
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Kusneirczyk P.Genetic differences between smokers and never-smokers with lung cancer.Front Immunol.2023;14:1063716. doi:10.3389/fimmu.2023.1063716LoPiccolo J, Gusev A, Christiani DC, Janne PA.Lung cancer in patients who have never smoked — an emerging disease.Nat Rev Clin Oncol. 2024 Feb;21(2):121–146. doi:10.1038/s41571-023-00844-0American Cancer Society.Special section: lung cancer.Pelosof L, Ahn C, Goa A, et al.Proportion of never-smoker non-small cell lung cancer patients at three diverse institutions.J Natl Cancer Inst.2017 Jan 28;109(7):djw295. doi:10.1093/jnci/djw295Yale Medicine.Non-small celll lung cancer.American Cancer Society.Lung cancer risks for people who don’t smoke.Centers for Disease Control and Prevention.Protect yourself and your family from radon.Centers for Disease Control and Prevention.Health effects of secondhand smoke.Yale Medicine.Lung cancer in non-smokers.Shankar A, Dubey A, Saini D, et al.Environmental and occupational determinants of lung cancer.Transl Lung Cancer Res. 2019 May;8(Suppl 1):S31-S49. doi:10.21037/tlcr.2019.03.05Xue Y, Jiang Y, Jin S, Lin Y.Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis.Onco Targets Ther.2016;9:2987–2992. doi:10.2147/OTT.S100949American Lung Association.How is lung cancer diagnosed?Centers for Disease Control and Prevention.Lung cancer among people who never smoked.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Kusneirczyk P.Genetic differences between smokers and never-smokers with lung cancer.Front Immunol.2023;14:1063716. doi:10.3389/fimmu.2023.1063716LoPiccolo J, Gusev A, Christiani DC, Janne PA.Lung cancer in patients who have never smoked — an emerging disease.Nat Rev Clin Oncol. 2024 Feb;21(2):121–146. doi:10.1038/s41571-023-00844-0American Cancer Society.Special section: lung cancer.Pelosof L, Ahn C, Goa A, et al.Proportion of never-smoker non-small cell lung cancer patients at three diverse institutions.J Natl Cancer Inst.2017 Jan 28;109(7):djw295. doi:10.1093/jnci/djw295Yale Medicine.Non-small celll lung cancer.American Cancer Society.Lung cancer risks for people who don’t smoke.Centers for Disease Control and Prevention.Protect yourself and your family from radon.Centers for Disease Control and Prevention.Health effects of secondhand smoke.Yale Medicine.Lung cancer in non-smokers.Shankar A, Dubey A, Saini D, et al.Environmental and occupational determinants of lung cancer.Transl Lung Cancer Res. 2019 May;8(Suppl 1):S31-S49. doi:10.21037/tlcr.2019.03.05Xue Y, Jiang Y, Jin S, Lin Y.Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis.Onco Targets Ther.2016;9:2987–2992. doi:10.2147/OTT.S100949American Lung Association.How is lung cancer diagnosed?Centers for Disease Control and Prevention.Lung cancer among people who never smoked.
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Yale Medicine.Non-small celll lung cancer.
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Centers for Disease Control and Prevention.Protect yourself and your family from radon.
Centers for Disease Control and Prevention.Health effects of secondhand smoke.
Yale Medicine.Lung cancer in non-smokers.
Shankar A, Dubey A, Saini D, et al.Environmental and occupational determinants of lung cancer.Transl Lung Cancer Res. 2019 May;8(Suppl 1):S31-S49. doi:10.21037/tlcr.2019.03.05
Xue Y, Jiang Y, Jin S, Lin Y.Association between cooking oil fume exposure and lung cancer among Chinese nonsmoking women: a meta-analysis.Onco Targets Ther.2016;9:2987–2992. doi:10.2147/OTT.S100949
American Lung Association.How is lung cancer diagnosed?
Centers for Disease Control and Prevention.Lung cancer among people who never smoked.
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