Lung Cancer Causes & Risk Factors

We don't always know what causes lung cancer. However, it is important to understand certain causes and risk factors for developing lung cancer.

Lung Cancer: Causes And Risk Factors

Some risk factors, like personal and family history, you can't control. Others are within your power to change. For example, quitting smoking is something you can do to dramatically lower your risk of getting lung cancer.

Tobacco And Lung Cancer: Quit Smoking For Your Lung Health

Smoking is by far the leading risk factor for lung cancer. Tobacco smoke causes nearly nine out of 10 cases of lung cancer. Some important tobacco facts:

  • The longer a person has been smoking and the more packs per day smoked, the greater the risk.
  • Smoking low tar or "light" cigarettes increases lung cancer risk just as much as regular cigarettes do.
  • Menthol cigarettes may increase the risk even more since the menthol allows smokers to inhale more deeply.
  • Cigar and pipe smoking are almost as likely to cause lung cancer.
  • If a person stops smoking before lung cancer starts, the lung tissue slowly returns to normal. Stopping smoking at any age lowers the risk of lung cancer.

Secondhand smoke is also a risk factor. Even if you don't smoke, but you breathe the smoke of others, you are at a higher risk for lung cancer. Non-smoking spouses who live with a smoker have about a 20 to 30 percent greater risk of developing lung cancer than do spouses of non-smokers. Non-smokers exposed to tobacco smoke in the workplace are also more likely to get lung cancer

Other Lung Cancer Causes And Risk Factors

In addition to tobacco smoke, other risk factors for lung cancer include:

  • Radon. Radon is a radioactive gas made by the natural breakdown of uranium in soil and rocks. Radon can't be seen, tasted or smelled. It can build up indoors and create a possible risk for cancer. The risk is much higher among smokers. Offices of the Environmental Protection Agency can give you information on how to test for radon in the home.
  • Asbestos. People who work with asbestos have increased risk of getting lung cancer. Smoking significantly increases the risk. Both smokers and non-smokers exposed to asbestos are at risk of getting a type of cancer called mesothelioma, which starts in the lining of the lungs. The government has now nearly ceased its use of asbestos in the workplace and in home products. Though it is still present in many buildings, it is not harmful as long as it is not released into the air.
  • Other workplace hazards. Workplace carcinogens that can increase lung cancer risk include diesel exhaust, radioactive ores (such as uranium) and inhaled chemicals or minerals, such as arsenic, beryllium, cadmium, vinyl chloride, nickel compounds, chromium compounds, coal products, mustard gas and chloromethyl ethers. The government and industries have taken recent steps to protect workers, but the dangers are still there. If you work around any of these, you should limit your exposure as much as possible.
  • Chest radiation treatment. People who have had radiation to the chest to treat another cancer are at higher risk for lung cancer, especially if they smoke. Women who have radiation to the breast after a lumpectomy for breast cancer do not appear to have a higher risk of lung cancer.
  • Arsenic. High levels of arsenic in drinking water may increase the risk of lung cancer. The risk is even greater for smokers.
  • Personal and family history. If you have had lung cancer, you have a higher risk of getting another lung cancer. Close blood relatives of people who have had lung cancer may have a higher risk themselves. Genes do seem to play a role in some families with a strong history of lung cancer.
  • Diet and vitamins. Two studies found that smokers who took beta carotene supplements had an increased risk of lung cancer.
  • Air pollution. Air pollution may slightly increase the risk of lung cancer, though the risk is still far less than that caused by smoking. About five percent of all deaths from lung cancer worldwide may be attributable to outdoor air pollution.
  • Marijuana. It has been hard to study whether there is a link between marijuana and lung cancer, because it is not easy to gather information about the use of illegal drugs. However, there is evidence that marijuana could cause cancers of the mouth and throat. Marijuana cigarettes have more tar than regular cigarettes, and many of the cancer-causing substances in tobacco are also found in marijuana. Marijuana uses inhale very deeply and hold the smoke in the lungs for a long time. Therefore, it is possible that smoking marijuana can increase risk of lung cancer.