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Lung cancer is the leading cancer killer in America for both men—and women. (Nope, it’s not breast cancer.) And despite lung cancer’s reputation as “the smoker’s curse,” more than 20 percent of Americans who died from lung cancer in 2017 reported having never smoked in their lives, according to the American Cancer Society. In fact, if lung cancer in non-smokers were its own separate category, it would rank among the top 10 fatal cancers in the United States, the ACS notes.
Overall, about 10 to 15 percent of lung cancers occur in people who’ve never smoked, which, for many, is a surprising and shocking statistic.
“People often want to know why they got lung cancer if they never smoked, and as hard as it can be to accept, often we simply don't know,” says Suzanne Dixon, MPH, an epidemiologist at The Mesothelioma Center.
While not smoking certainly dramatically lowers your risk of getting lung cancer (as well as many other kinds of cancer), it’s not the only risk factor at stake. Scientists are still learning the complex mix of environmental and genetic factors that put someone at risk for lung cancer. So it’s important for everyone (whether you smoke a pack a day or never lit up a single cigarette) to know some basic facts about lung cancer risks and how to minimize them.
The majority of lung cancers in non-smokers are called adenocarcinomas, which is a type of non-small cell lung cancer. The predominant type of lung cancer in smokers is squamous cell lung cancer (also a type of non-small cell lung cancer). Squamous cell lung cancers tend to cause more obvious symptoms, like coughing, earlier on in the course of disease because they develop closer to the airways. On the other hand, adenocarcinomas tend to grow in the outer areas of the lungs, so it can take longer before symptoms show up. This helps explain why lung cancer in non-smokers tends to be diagnosed at later stages when it can be more difficult to treat. Learn more about types of lung cancer here.
While anyone with lung cancer can have any kind of lung cancer symptom, smokers are more likely to experience red-flag, obvious symptoms like coughing, coughing up blood, or infections (like bronchitis or pneumonia) that won’t go away. Non-smokers may have more vague symptoms of lung cancer, such as shortness of breath (which is easy to dismiss or blame on another issue, like a heart problem or asthma), chest pain, or fatigue.
Lung cancers in non-smokers often have gene changes that are different from those in cancers in smokers. Understanding how gene changes cause lung cancer cells to grow is helping researchers develop new, targeted therapies and drugs that specifically target these mutations, according to the ACS.
Everyone diagnosed with non-small cell lung cancer should have gene testing on their tumors. This can uncover genetic mutations, such as EGFR, which leads to certain proteins on cancer cells that can contribute to their growth. There are different targeted therapies that can treat EGFR positive lung cancer. EGFR mutations are more common in non-smokers as well as in women. Other specific genetic mutations appear to be more common in non-smokers as well.
More men are diagnosed with lung cancer each year than women, and lung cancer is also more likely to be fatal in men, according to the ALA. There appear to be important differences in the ways lung cancer develops in women versus in men, according to a report from Harvard Health Publishing. For one thing, the most common lung cancer in women is adenocarcinoma; in men, the most common kind of lung cancer is squamous cell carcinoma, which tends to produce more symptoms (see above).
Women non-smokers may be more vulnerable to lung cancer than non-smoking men; two-thirds of non-smokers with lung cancer are women. According to the Harvard report, “some of the differences in the development of the disease may be explained by genetic and hormonal factors, possibly in combination. Women are more likely than men to have certain genetic mutations associated with lung cancer risk.” The hormone estrogen, for example, may play a role in cancer growth.
Unfortunately only about 16 percent of lung cancers are discovered in the early, most treatable stage, according to the American Lung Association. Once the cancer has spread to other organs, the survival rate drops considerably. Routine screenings for lung cancer aren’t recommended for the general population, so for non-smokers, the best thing you can do is be on the lookout for possible lung cancer symptoms—chronic, raspy coughing; respiratory infections that keep coming back, shortness of breath that doesn’t get better, wheezing, hoarseness, and chest pain, for example.
If you don’t smoke, you may mistake such symptoms for asthma or other issues, so it’s important to see your doctor about anything that seems out of the norm for you.
The leading cause of lung cancer from environmental exposure (after cigarettes) is radon gas in your house, says Osita Onugha, MD, a thoracic surgeon and assistant professor of thoracic surgery at John Wayne Cancer Institute in Santa Monica, California. Radon is an odorless gas that is emitted naturally from the soil; how much you’re exposed to depends on where you live.
Scientists estimate that 15,000 to 22,000 lung cancer deaths in the United States each year are related to radon, according to the National Cancer Institute.
Check if your home is in a radon hot spot by checking out the EPA’s radon zone map or by purchasing a radon test kit from your local hardware store. If high levels of radon are found in your home, call your state EPA office to get a list of qualified radon mitigation contractors. They can install a system to remove the radon from your home and advise you on how to do ongoing testing to ensure your radon levels are safe.
You may not smoke, but if anyone around you does—especially someone you live with—you are still at a higher risk for developing lung cancer, says Kien Vuu, MD, a clinical professor of interventional and diagnostic radiology at UCLA, Olive View Medical Center. It’s estimated that more than 40,000 non-smoking Americans die every year from secondhand smoke, according to the Centers for Disease Control. Helping a loved one to quit smoking is one of the best things you can do for your health, not to mention theirs, he says. At the very least, do your best to limit your exposure to any secondhand smoke.
“As an oncology dietitian, I want people to know how important nutrition is both for preventing cancer and during cancer treatment,” says Courtney Meidenbauer, RDN, a registered dietitian nutritionist and a board-certified specialist in oncology nutrition. A 2016 study from researchers at M.D. Anderson Cancer Center in Houston compared dietary habits of 1,905 patients who were newly diagnosed with lung cancer with 2,413 healthy people from nearby medical clinics. The researchers found that people who ate diets high on the glycemic index had a greater risk of developing lung cancer than people who ate low-GI diets. A high-GI diet is full of simple carbohydrates that rapidly spike your blood sugar, like soda. (Learn more about the difference between complex and simple carbs here.) Those who ate a lot of fruits and vegetables also had a decreased risk of lung cancer compared with those who didn’t.
While the study doesn’t prove that one’s diet choices cause or prevent lung cancer, and more research is needed to understand the ways fooods can affect lung cancer risk, the study authors the authors suggest “limiting foods and beverages with high GI, such as white bread or bagels, corn flakes and puffed rice, for a more balanced diet and to lower the risk for lung cancer and chronic diseases.”
Lung cancer is the country’s number-one cancer killer, so it’s understandable that getting a lung cancer diagnosis can seem grim. But it’s important to look at the positive statistics too: Half of patients diagnosed in the early stages of lung cancer recover, according to the American Lung Association. “New targeted therapies are showing remarkable results in shrinking tumors in lung cancer patients,” Dixon says. “If you take care of yourself, you'll be in the best possible position to benefit from all treatment options available to you.”
Some research indicates that non-smokers with lung cancer have better survival rates than current or former smokers. (It’s also important to note that smokers who get lung cancer and quit smoking during treatment have better outcomes than those who still smoke; in other words, it’s never too late to quit smoking, ever.)
While smoking is the biggest risk factor for lung cancer that’s under your control, the truth is that only 10 percent of lifelong smokers are ever diagnosed with lung cancer, according to the ACS. This doesn’t mean you should condone smoking in friends or family members (it also increases your risk of other cancers, as well as heart disease, stroke, and diabetes, among many other things), but rather recognize that there are many factors that influence whether or not someone gets lung cancer. Blaming all lung cancer on smoking is a risky ignorance.