About 20% of people who have lung cancer have never smoked. Even many of these people are diagnosed with the disease when it is in an incurable stage.
Cancer experts have warned of the danger after publishing a report in the Journal of the Royal Society of Medicine that says there is an increasing number of non-smokers being diagnosed with lung cancer. Although smoking is the largest risk factor for developing lung cancer, the American Cancer Society estimates that up to 1 in 5 people with lung cancer in the United States have never smoked.
"There is no definitive answer as to why non-smokers develop lung cancer," Dr. told Healthline. Giorgio Scagliotti, president of the International Association for the Study of Lung Cancer and professor of oncology at the University of Turin. "However, there are some key risk factors outside of smoking associated with lung cancer."
Second hand smoke
Lung cancer can be the result of exposure to other smokers. Inside or out, there is no safe level of exposure to second-hand smoke. The U.S. Centers for Disease Control and Prevention defines secondhand smoke as "a combination of second-hand smoke and smoke inhaled by smokers."
Secondhand smoke contains hundreds of toxic chemicals, 70 of which are known to cause cancer and may be the single most important factor in preventing lung cancer in non-smokers.
Radon is a silent killer
Smoking is the number one preventable factor in the development of lung cancer. But he is not the only one. Exposure to radon (a chemical element) is the second leading cause of lung cancer.
"Radon exposure is ubiquitous on earth, so there is a greater incidence of radon exposure in those who work underground and from people whose homes have basements," Scagliotti said.
Air pollution a cause of cancer
In 2013, the World Health Organization (IARC) International Agency for Research on Cancer reported that air pollution was the leading environmental cause of cancer deaths. IARC monographs are a source of scientific evidence on cancer-causing substances and exposures. Air pollution can be difficult to avoid.
Sources: Healthline, Health, WebMD
