Ask an expert: Why do nonsmokers get lung cancer?

Q: “I know two women who have lung cancer, and neither of them has ever smoked. How could this happen to them? I thought lung cancer was caused by smoking.”

Answered by Rachel Sanborn, M.D., medical oncologist and medical director of the Providence Thoracic Oncology Program at Providence Cancer Institute; and medical director of the Phase I Clinical Trials Program at the Earle A. Chiles Research Institute, a division of Providence.

I wish I could say that if you never smoked, you'd never get lung cancer. It's true that if we eliminated tobacco, we could prevent about 90 percent of future lung cancers in the United States. However, it wouldn't prevent all of them. There are many other risk factors which can cause lung cancer. About 10 percent of men and 20 percent of women who develop lung cancer in the United States have never smoked.

While tobacco is by far the leading cause of lung cancer, it's not the only contributor. In the United States, the second leading cause – and the most common cause in nonsmokers – is radon. This naturally occurring radioactive gas seeps into homes from the ground and can build up to levels that are high enough to cause lung cancer. The U.S. Environmental Protection Agency, or EPA, estimates that this very common, colorless, odorless gas is responsible for as many as 21,000 lung cancer deaths in our country each year.

Secondhand smoke – the smoke that we inhale from other people's cigarettes –plays a role as well. Nonsmokers who are exposed to secondhand smoke increase their risk of developing lung cancer by 20 to 30 percent. People who grew up in smoking households are at particularly high risk. They were exposed to cancer-causing agents on a regular basis while their lungs were still developing. When we see lung cancer in nonsmokers in their 30s and 40s, the most likely causes are early exposure to household cigarette smoke or radon. 

A third, and increasing, contributor is environmental pollution. The World Health Organization cites air pollution as the world's worst environmental carcinogen. While this is a bigger problem in industrialized regions with fewer pollution controls, such as China and East Asia, air pollution still plays a problematic role in the U.S. as well. 

What makes lung cancer so devastating is that it strikes in a place you can't see and causes changes that you can't feel. In nonsmokers, it is so unexpected that it's not usually discovered until symptoms do arise, and by then, it may be very advanced.

Lung cancer is the No. 1 cause of cancer deaths worldwide, but it's in our power to change that. We can reduce the number of deaths from this disease, both in smokers and in nonsmokers, by talking about it, being aware of it and working together to take action. Here are six things you can do.

Six ways to protect yourself and your family

1. Test your home for radon. Radon testing is incredibly important. The EPA estimates that one of every 15 homes in the U.S. has unsafe radon levels. According to the Oregon Health Authority, some areas in Oregon, particularly in the Portland metropolitan area, are at high risk of elevated radon levels. In Multnomah County, it's closer to one in three; 28 percent of homes, as well as 16 percent of homes in Clackamas County and 11 percent of homes in Washington County, have unsafe radon levels. (Check your county's statistics here.) Conducting radon tests is easy and the best time to do it is during winter months. Inexpensive test kits are available at most home improvement stores. If your radon test result is high, work with a certified radon mitigation professional to improve your home. And spread the word among your friends and family members.

2. Avoid smoking and secondhand smoke. The biggest impact we can make on reducing lung cancer is by eliminating tobacco use and tobacco exposure. Make your home a no-smoking zone and support indoor clean air acts and anti-smoking legislation. Take advantage of every resource to help a smoker quit for good.

3. Educate your kids about the harms of tobacco use. Nearly everyone addicted to tobacco today started the habit as a teenager. If you can help the young people in your life resist smoking and vaping through their teen years, there is a strong likelihood that they will remain smoke-free for life. Read this important article on how to keep kids from using tobacco.

4. Work to reduce pollution. We know that exposure to diesel exhaust and other pollutants increases the risk of lung cancer. Any action you can take to support clean air and water is hugely important to your health and the health of everyone you care about.

5. Eat for your health. Shift your eating habits toward a Mediterranean-style diet, which focuses on vegetables, fruits and whole grains. This has been shown to reduce cancer risks, as well as risks for heart disease, diabetes and obesity. Follow our nutrition blog for healthy eating tips and resources.

6. If you currently smoke or have smoked, talk with your doctor about lung cancer screening. The U.S. Preventive Services Task Force recommends yearly, low-dose computed tomography (LDCT) screening for people between the ages of 50 and 80 who've smoked the equivalent of a pack a day for 20 years or longer, even if they've quit in the last 15 years. Evidence shows that annual screening can reduce deaths from lung cancer by up to 20 percent by finding and treating it before it has grown and spread, and screening patients at a younger age and with lighter pack years of smoking shows a moderate clinical benefit in lung cancer screening.

It takes time for all health insurers to adopt cancer screening recommendations. If you have questions about your health insurance, contact your insurance provider to learn about your coverage for lung cancer screening.

Learn more about Providence Cancer Institute’s Lung Cancer Screening Program.

One more thing you need to know

Another very important thing to know is that not everyone who gets lung cancer dies from it. Treatment does help, some cancers can be cured, and we are learning more all the time. The researchers at Providence Cancer Institute are pioneering new ways to help the body's immune system fight cancer. Multiple clinical trials of new, targeted therapies for lung cancer are also happening at the center right now.

It's a very exciting time to be in this field, particularly with the recent breakthroughs that we have seen in immunotherapy. There is a lot more promise now than we've seen before, and that's very encouraging.

To learn more about our team of lung cancer experts, visit the Providence Thoracic Oncology Program.

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