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How Lung Cancer Can Affect People Who Have Never Smoked

A pulmonologist discusses various environmental and health factors that can contribute to lung cancer risk, and what you can do to be proactive.

If you’ve ever thought, “lung cancer will never affect me,” just because you’ve never smoked, you’re not alone; however, experts urge you to think again. Even non-smokers – who are people defined as having smoked zero or fewer than 100 cigarettes in their lifetime – face the potential development of what is the third most common cancer in the United States.  

In the U.S. alone, statistics show that 10-20% of diagnosed lung cancer cases (nearly 20-40,000) occur in non-smokers. Why is this?  

It’s a complicated interplay of various factors, explains Julie A. Barta, MD, Jefferson Health pulmonologist. Studies are inconclusive on whether there is a true rise in lung cancer prevalence among non-smokers, and how this may be influenced by an overall decrease in smoking rates.  

So, what can you do about your lung cancer risk if you don’t smoke? Many complex risk factors come into play, including other respiratory illnesses; carcinogenic exposures; occupational hazards; secondhand and thirdhand smoke; and genetics.  

The Role of Other Illnesses 

When talking about cancer risk in general, we often consider what we’re exposed to, notes Dr. Barta, but not what illnesses we already have. Common respiratory illnesses, such as COPD (chronic obstructive pulmonary disease), emphysema, and pulmonary fibrosis, can independently increase our risk for lung cancer.  

“Even though these conditions can be caused by smoking and co-exist with lung cancer, the damage and scarring that each cause to the lungs increases the risk for cancer by two to five-fold,” explains Dr. Barta. “Proper management with a specialist can help you stay on top of your risk.”  

What We’re Exposed To  

Radon and asbestos are two leading carcinogens credited for causing lung cancer; these can appear in the home environment, usually after renovations or when things haven’t been assessed properly. If you are planning renovations, or if your home hasn’t been checked in a while, it might be wise to give it a look, suggests Dr. Barta. Similarly, if you work in construction, textile, or shipyard industries, it’s believed you’re at higher risk for these exposures.  

Prior radiation exposure, particularly to or around the chest region (i.e., for breast cancer treatment) is also known to have an impact. Though modern technologies have allowed for radiation to be much more targeted and avoid uninvolved tissue, you can still end up with some scarring in the lungs, adds Dr. Barta.  

Secondhand Smoke 

If you simply walk past someone on the street who is smoking, it’s not so problematic. However, if you live with/spend significant time around someone who smokes, secondhand smoke may be your biggest risk factor.  

The cloud of smoke exhaled contains many of the same carcinogens that those who smoke inhale, says Dr. Barta. Cigarettes contain upwards of 100-plus toxic substances; the way lung cancer develops from this is that these carcinogens bind to DNA and cause abnormalities. It’s been proven that those who are exposed to secondhand smoke have carcinogens in their urine, so we know exposure is real.  

Secondhand smoke can lead to other health impacts besides increased lung cancer risk – cardiovascular disease and stroke are the biggest ones. Stroke is incredibly prevalent in those who live with a spouse who smokes. Studies show that spousal exposure can lead to a 27% increase in stroke in women.  

Reducing your exposure is often easier said than done, as it can be an emotionally trying journey to help a loved one quit smoking, says Dr. Barta. “I try to give my patients practical tips. Tobacco treatment support groups can be a welcoming and understanding environment to help one cut down or quit. In the meantime, if they struggle to quit, smoking outside the home whenever possible can help reduce exposure.”  

Genetics & More  

“When we look at the role of genetics in lung cancer, we don’t know as much about the role of family history and inherited genes as we do for some other cancers,” says Dr. Barta, “though those with first-degree relatives with lung cancer do have an increased risk.”  

There are some acquired DNA alterations (which aren’t passed down), such as EGFR mutations or ALK (anaplastic lymphoma kinase) translocations (gene rearrangements) that can occur more commonly, specifically in adenocarcinoma (the most common type of lung cancer in the U.S.) and in individuals without a smoking history. 

It’s been documented that female non-smokers are also susceptible to lung cancer, adds Dr. Barta, which has given rise to studies on the endocrine system/hormones, the role of hormone replacement therapy (we know this has an impact on breast cancer), and other gender-related factors.  

What You Can Do  

At this time, lung cancer screenings, via low-dose CT scans, are not recommended for non-smokers. The current guidelines cover those aged 50-80 with a 20 pack-year smoking history, including anyone who has quit within the last 15 years.  

The most important thing you can do, as a non-smoker, is to have an open and continuous dialogue with your healthcare provider(s) about your history of exposure, current exposures, and any other risk factors or concerns, urges Dr. Barta. Sometimes patients have a CT scan for another reason, and lung nodules may be found. Although, most incidentally detected lung nodules are not caused by cancer, all factors are considered when evaluating lung nodules.  

In cases where an incidental lung nodule does turn out to be cancer, early-stage disease is curable. Moreover, lung cancers that are small don’t typically cause symptoms, which is why it’s ideal to discuss lung cancer risk and nodule management before symptoms – such shortness of breath, weight loss, or coughing up blood – appear.  

“I think many people are scared to have these conversations, because the stigma around lung cancer specifically is so strong,” continues Dr. Barta. “We want you to bring your concerns to our attention as soon as possible. It may not be lung cancer, but the earlier we can evaluate a nodule and decide on a management strategy, the better.”  

For the benefit of your overall health, remember to be proactive. Know what might put you at risk and how to reduce your exposure or avoid it completely. Make healthy lifestyle choices, including diet, physical activity, and recommended vaccinations, and protect your lungs as much as possible.  

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