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.[1]
Up to 20 percent of people who die from lung cancer each year have never smoked or used any form of tobacco.[2]
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.[3]
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.[4]
“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.[5]
It’s important to remember that smoking is still the leading cause of adenocarcinoma.[6]
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.[5]
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.”[3]
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.[3]
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.[3]
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.[7]
“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.[8]
“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.[9]
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.[3][5]
Radon exposure is the second leading cause of lung cancer but the most common cause of lung cancer in nonsmokers.[10]
Some recent studies have suggested that modern building construction practices have led to an increase in the amount of radon concentration in homes.[11]
The Environmental Protection Agency estimates that 1 in 15 homes in the United States has unsafe levels of radon.[12]
Other Environmental Pollutants
Other environmental factors may lead to lung cancer in people who don’t smoke, such as exposure to:[5]
- 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:[6][13]
- 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.
Resources We Trust:
- Cleveland Clinic: Non-Small Cell Lung Cancer, Precision Medicine
- National Cancer Institute: Treatment Clinical Trials for Non-Small Cell Lung Cancer
- American Lung Association: Find a Clinical Trial
- European Society for Medical Oncology: Personalised Medicine at a Glance: Lung Cancer
Important Notice: This article was originally published at www.everydayhealth.com by Julie Lynn Marks and Ana Sandoiu where all credits are due. Medically reviewed by Tingting Tan, MD, PhD
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