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 co-director of the Providence Thoracic Oncology Program

I wish I could say that if you never smoked, you'd never get lung cancer. It's true that if we eradicated tobacco, we could prevent about 85 percent of future lung cancers – but that wouldn't prevent all of them. About 10 percent of men and 20 percent of women who develop lung cancer 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 22,000 lung cancer deaths in our country each year.

Secondhand smoke – the smoke that we inhale from other people's cigarettes – definitely plays a role as well. People who grew up in smoking households are at particularly high risk, because 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 contributor is environmental pollution. The World Health Organization cites air pollution as the world's worst environmental carcinogen, responsible for some 223,000 deaths from lung cancer worldwide in 2010. While this is a bigger problem in industrialized regions with fewer pollution controls, such as China and East Asia, air pollution still plays a supporting 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's usually very advanced and, in most cases, no longer curable. 

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, especially with the high levels of radon that we see in Oregon, and particularly in the Portland metropolitan area, because of our geological composition. The EPA estimates that one of every 15 homes in the U.S. has unsafe radon levels. In Multnomah County, it's closer to one in three; 32 percent of homes in Multnomah County, as well as 19 percent of homes in Clackamas County and 13 percent of homes in Washington County, have unsafe radon levels. (Check your county's statistics here.) Testing is easy, and now is a good time to do it, before warmer weather has you opening windows and increasing the air circulation in your house. Inexpensive test kits are available at most home improvement stores. If your result comes back showing higher levels of radon, there are several companies in the Portland area that install fairly simple removal systems. Learn more about radon testing and removal here. 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. If there is a smoker in your household, there is no better motivator to quit than the health of your children. Take advantage of every resource to help a smoker quit for good.

3. Make sure your kids don't become smokers. Nearly everyone addicted to tobacco today started the habit as a teenager. If you can help the young people in your life resist smoking 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 smoking.

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. 

6. If you smoke or smoked, get screened. New guidelines recommend yearly, low-dose CT screening for people between the ages of 55 and 80 who've smoked the equivalent of a pack a day for 30 years, even if they've quit in the last 15 years. New evidence shows that annual screening can reduce deaths from lung cancer by 20 percent by finding and treating it before it has grown and spread. Learn more about Providence Cancer Center's Lung Cancer Screening Program.

Two more things you need to know

Lung cancer is a highly stigmatized disease, and that's unfair. As you've discovered, not everyone who gets lung cancer is a smoker. Among those who are smokers, the vast majority fell prey to this powerful addiction as the result of what seemed like harmless teenage experimentation with tobacco. Regardless of a person's smoking history, nobody deserves this.

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 Center are pioneering new ways to help the body's immune system fight cancer. Multiple clinical trials of new, targeted therapies for lung cancer are happening at the center right now. One of these is testing a lung cancer vaccine that was developed by our own researchers – the vaccine is given to people who have been treated for stage 3 lung cancer to help their immune systems recognize their cancer and try to keep it from coming back.

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.