Why non-smokers are getting lung cancer

Lung cancer, one of the deadliest cancers in the world, is not just impacting people who smoke.

"Anyone that has lungs has a chance of lung cancer,” says Jun Zhang, MD, PhD, vice president of oncology research with OSF HealthCare Cancer Institute.

In fact, 10-20% of lung cancer patients are people who have never even smoked, Dr. Zhang adds. 

"Lung cancer is generally referred to as a 'smoker's disease.' But it turns out now that we're seeing more lung cancer patients without a history of smoking," Dr. Zhang observes. "If we put lung cancer in patients who have never smoked in a separate category, this can be listed as the number five cancer killer in the world." 

This translates to roughly 40,000 Americans every year being diagnosed with lung cancer, despite never smoking cigarettes. 

Women of Asian descent who don't smoke tend to be impacted more by this, Dr. Zhang says, compared to the rest of the population. Research shows that 57% of Asian American women diagnosed with lung cancer have never smoked. Based on this, in a recent study called FANS (Female Asian Never Smoker), researchers at the University of California San Francisco (UCSF), UC Davis and Stanford University are investigating why Asian American women who have never smoked develop lung cancer at unusually high rates compared with other populations.

Sadly, Dr. Zhang says, people who present with lung cancer but have never smoked, are presenting at a later stage. 

"Those patients present to us, at least at my clinic, and they already missed the chance of an early diagnosis. Early symptoms can be cough and shortness of breath, but quite often people are not paying attention to this because they don't smoke and they don't have a chance to get screened," Dr. Zhang says. "That's the sad story, that even though they've never smoked, at the time when they're diagnosed with lung cancer, it's almost always at late stage." 

So, why is this happening? Dr. Zhang discusses five main reasons that non-smokers are getting diagnosed with late-stage lung cancer. The top two culprits will be laid out in this article, with three more to come in part two.

#1: PM2.5 (Particulate Matter)

PM2.5 is the top contributor to non-smokers diagnosed with lung cancer worldwide. The U.S. Environmental Protection Agency (EPA) describes PM2.5 as fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.

"If you inhale the particles, you cannot get them out of your body. It can get into your lungs, be trapped there, and even get into your circulation and cause problems," Dr. Zhang says. "If we're thinking about cigarette smoking as the number one reason for lung cancer, globally PM2.5 is the second most common reason for lung cancer." 

In the United States, the EPA sets and reviews national air quality standards for PM2.5.

The Upper Midwest region has been below the national average for many years, and according to the EPA, has seen an improvement in air quality since at least 2000. The EPA's national standard is set at 9.0 micrograms per cubic meter. Dr. Zhang says for every 10 microgram per cubic meter increase, it increases lung cancer mortality by 20%.

Some areas in the world can be up to 100 micrograms per cubic meter; Dr. Zhang points out. Vehicle exhaust and industrial emissions along with outdoor fires contribute to these levels. 

The American Cancer Society (ACS) reports lifetime exposure to PM2.5 might increase the risk, and even speed up the onset of various cancers, including lung cancer.

#2: Radon levels in the home

While high PM2.5 levels are the #2 cause of lung cancer worldwide, here in the United States, the second-leading cause of lung cancer (next to smoking) is due to high radon levels. 

According to the ACS, radon is a colorless and odorless radioactive gas. Radioactive elements such as uranium found in soil and rock break down, then move the radon gas from the soil and rock into the air, ground water and surface water.

When radon breaks down in the air, it gives off radiation that can damage DNA in our cells.

“Radon is released by radioactive materials underground, but then they accumulate in the house, especially if it doesn't have good ventilation," Dr. Zhang says. 

The U.S. Centers for Disease Control & Prevention (CDC) says testing for radon in your home is the only way to know if levels are high. It’s recommended to get this testing done before or as soon as you move into the home.

Dr. Zhang says findings like this argue for expansion of lung cancer screening criteria. 

He adds that if you have any concerns like lingering cough that lasts for multiple weeks, especially with shortness of breath, talk to your primary care provider (PCP). You can get a chest X-Ray to make sure you don't have pneumonia.

GERD (acid reflux) and some heart issues could also be a possibility, and these are important to check out. If none of these things exist, this is where patients should advocate for themselves and ask for a CT scan to check for lung cancer that can show if a nodule or mass is present.

To learn more about the Lung Cancer Program at OSF Cancer Institute, or to schedule an appointment, visit the OSF HealthCare website.

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