Nearly 20 percent of women and eight percent of men with lung cancer have never smoked, say researchers involved in a study of one million people in the United States and Sweden. The likely culprit in these lung cancer cases is secondhand smoke.It's not yet clear why women are more likely to develop the disease. Perhaps they are more susceptible to all forms of smoking -- whether direct or secondhand -- or maybe because more men smoke than women, women are more likely to be exposed to secondhand smoke.
While smoking is the leading cause of lung cancer, there are other factors to blame for disease incidence. Radon, asbestos, chromium, and arsenic are all associated with lung cancer.
According to the American Cancer Society, lung cancer will be diagnosed in 213,000 Americans in 2007. The disease will kill 160,000.
