“Twenty percent of lung cancer cases in the United States are diagnosed in people who never smoked.
“This translates to between16,000 and 24,000 Americans annually, according to the American Cancer Society. The majority of these cases are non–small cell lung cancer.
“Although the exact cause for increased proportion of lung cancer cases among never-smokers has not been established, researchers suggest environmental factors may to be blame.
“However, they emphasize more data are needed to identify the factors that are driving the increase ― and determine the most appropriate treatment options for never-smokers ― before changing practice.”