Lung Cancer Risk Stable for Nonsmokers

By Robert Shmerling, M.D.
Content provided by the Faculty of the Harvard Medical School

Lung cancer risk among people who don't smoke has stayed the same since the 1930s. And of the nonsmokers who get this disease, men are more likely to die. Those are among the findings of a large international study. It included information from nearly 2 million people around the world. Men who had never smoked had a 1.1% percent risk of lung cancer death. The risk was 0.8% for women. HealthDay News wrote about the study September 9. It was published in the journal PLoS Medicine.

What Is the Doctor's Reaction?

Do you think of lung cancer as something that affects only smokers?

It's understandable if you do. Compared with nonsmokers, a person who smokes has a 13-fold increase in the risk of developing lung cancer. It's estimated that 22% of men who smoke cigarettes now will die of lung cancer before age 85. For women who smoke, the risk of death due to lung cancer is 12%.

But lung cancer does occur in people who have never smoked. In fact, nonsmokers account for 10% to 15% of lung cancer cases. As smoking rates have dropped in recent years, the number of nonsmokers has increased. So, there is concern that cases of lung cancer among nonsmokers might also increase. Getting a better handle on these cases is important.

A new study attempts to do just that. Researchers from the American Cancer Society gathered data on 1.8 million nonsmokers from North America, Asia and Europe. Here's what they found:

  • Lung cancer deaths of nonsmokers are more common among men than women.

  • Nonsmoking African-Americans and Asians living in Asia have a higher death rate from lung cancer than other ethnic groups.

  • Since the 1930s, the rate of lung cancer among nonsmokers has remained stable.

  • The overall risk of lung cancer death before age 85 was 1.1% for nonsmoking men and 0.8% for nonsmoking women.

Why do nonsmokers get lung cancer? This study did not address this important question. Other research suggests that these other factors increase the risk of lung cancer:

  • Exposure to secondhand smoke

  • Exposure to asbestos or radon gas

  • Exposure to work-related chemicals such as vinyl chloride, uranium or coal products

As I read this news, I was surprised by how common lung cancer is among nonsmokers. I was disappointed to learn that the rate had not decreased in the last few decades. I thought that certain improvements might have reduced lung cancer rates and deaths. These changes include:

  • Better protection of workers from dangerous exposures

  • Lower rates of smoking (which should reduce exposure to secondhand smoke)

  • Improvements in detection and medical care

Still, it's possible that several offsetting forces explain the results of this research. Improved means of detection cancer might lead to an apparent increase in lung cancer rates. Meanwhile, reduced secondhand smoke exposure might reduce the frequency of lung cancer.

Despite improvements in many aspects of medical care, we still have no highly effective treatments for lung cancer. So, perhaps it should not be surprising that the death rate among nonsmokers has not changed.

What Changes Can I Make Now?

You can make changes now to reduce your risk of lung cancer. The most important change you can make is to stop smoking. Better yet, don't start. This new research focuses on lung cancer among nonsmokers. But it would be a mistake to overlook cigarette use. It's the most common and powerful factor that increases risk for this deadly disease. If you have trouble quitting on your own, ask your doctor for help. There are many ways to do it, with or without medicines. Here are other steps you can take to reduce your risk of lung cancer:

  • Avoid secondhand smoke. If you can, choose restaurants that have a no-smoking policy. Insist that smokers in your home smoke outside.

  • Have your home inspected for asbestos. If asbestos is found, have it sealed or removed by professionals. Follow safety rules at work to limit your exposure. This also will limit exposure to those at home who may inhale asbestos you bring home on your clothing.

  • Reduce your exposure to radon gas. An estimated 1 in 15 homes in the United States have high radon levels. To test your home, place detectors in rooms that are at or below ground level. If radon levels are high, install a ventilation system. Have cracks in the floor or walls professionally sealed. If your water contains high radon levels, have it treated before it enters your home.

  • Follow safety procedures at work. These can limit your exposure to chemicals that cause lung cancer, such as vinyl chloride or uranium.

  • Choose a diet high in vegetables and fruit (although the overall benefit with respect to lung cancer risk is uncertain).

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