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Cancer is often hard to pin on a particular cause. Lung cancer, however, is one of the few that is clearly linked to a specific behavior: smoking.

“Smoking tobacco products is by far the leading cause of lung cancer, accounting for 90 percent of cases,” says Dr. Bryan Faller, a physician with Midwest Hematology Oncology Consultants and Missouri Baptist Cancer Center. That statistic accounts for most of the more than 226,000 new cases of lung cancer estimated in the United States this year, according to the American Cancer Society.

The other 10 percent of lung cancer cases may be linked to a variety of risk factors, including second-hand smoke, radon gas, asbestos and diesel exhaust exposure, family history and a prior lung cancer diagnosis.

Given the overwhelming evidence that smoking is the primary cause of most lung cancer cases, “smoking cessation is the greatest preventive strategy,” says Dr. Ramaswamy Govindan, an oncologist and lung cancer specialist with Washington University Physicians. For those who do stop smoking, he adds, “Over time, the risk decreases, but it can take years—10 to 20 years.”

Smokers and recent ex-smokers need to be especially diligent in monitoring their health. Govindan refers to a National Cancer Institute study, the National Lung Screening Trial (NLST), which compared low-dose CT scans to chest X-rays as screening tools in smokers. Results published in the New England Journal of Medicine indicated that participants who received the CT scans had a 20 percent decreased risk of dying from lung cancer than participants who received standard chest X-rays.

“Currently, screening is advocated only for cigarette smokers who are between the ages of 55 and 74 years old, have been smoking for at least 30 ‘pack-years’ and who continue to smoke or have quit within the past 15 years,” Faller says. “Low-dose CT scans of the chest performed annually for three years is recommended. This form of screening was recently found to be life-saving for this very high-risk group of patients,” he adds. To determine ‘pack-years,’ multiply packs of cigarettes smoked per day by the number of years smoked.

A persistent cough with no associated explanation, such as allergies or a cold, should be assessed by a physician. Other concerning symptoms include coughing up blood, unexplained shortness of breath and rapid, unexplained weight loss. “It doesn’t necessarily mean it’s cancer, but it’s something to check out,” Govindan notes. Other types of lung disease, such as emphysema, also are common in smokers and can share some of these symptoms.

The most important message from physicians and national health organizations is consistent: If you don’t smoke, don’t start; and if you do smoke, quit.


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