By Dennis Thompson
(HealthDay News) -- Not everyone who develops lung cancer does so because of smoking.
Smoking or being exposed to secondhand smoke causes the vast majority of lung cancers. The more people smoke and the longer they smoke, the greater their chances of developing the disease, reports the U.S. National Cancer Institute.
But people who never smoked or who had no prolonged exposure to secondhand smoke also develop the disease.
In these instances, the exact cause of a person's lung cancer can't always be determined. But cancer experts have identified certain factors that do increase risk. Besides exposure to tobacco smoke, they include, according to the cancer institute:
Radon. A radioactive gas that can't be seen, smelled or tasted, radon forms in soil and rocks. It can be present in houses in some parts of the country, and mineworkers also risk exposure to radon.
Asbestos, arsenic, chromium, nickel, soot and tar. The longer a person's exposure to such substances, the greater their risk. Most affected are people who work in the construction and chemical industries.
Air pollution. This is thought to slightly increase the risk for lung cancer.
Family history of lung cancer. People with a parent or sibling who had lung cancer may be at slightly increased risk for the disease, even if they don't smoke.
Personal history of lung cancer. Having had lung cancer slightly increases the risk for developing a second lung tumor.
Age. Most people are older than 65 when diagnosed with lung cancer.
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