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Risk Factors for Lung Cancer

A risk factor is something that increases your likelihood of getting a disease or condition.

It is possible to develop lung cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing lung cancer. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

Some factors such as age, gender, or ethnicity cannot be controlled. Almost all lung cancer is found in people over the age of 40 years, but it is most common in men after the age of 65 years. African-Americans, both men and women, carry a substantially higher risk of lung cancer than Caucasians.

It should be noted that although most lung cancers are associated with smoking, this cancer does occur in non-smokers.

Risk factors for lung cancer include:

Smoking

Nearly 85% of all lung cancers are associated with smoking. It is considered a direct and main cause. The lung tissue is exposed to a number of chemicals and carcinogens (cancer-causing agents) with every cigarette, pipe, or cigar. These carcinogens irritate and damage cells that line the respiratory tract and can alter the DNA of the cells. The damaged tissues also need more cell turnover than normal which increase the chance of abnormal growth. The risk of lung cancer increases with the number of years as a smoker and the number of cigarettes smoked.

Secondhand smoke inhaled by nonsmokers causes similar damage to lung tissue. As a result, those who are exposed to high amounts of second hand smoke also have an increased risk of lung cancer.

Occupational or Environmental Exposures

Exposure to asbestos is associated with a specific type of lung cancer called mesothelioma. For people who work (or worked) with asbestos, the risk is even higher among those who smoke. Other lung irritants, such as wood smoke, burning coal, mine dust, metals, or paint also increase the risk of lung cancer. These exposures can occur in the workplace or at home.

Radon is a radioactive gas that occurs naturally in the soil. It is a colorless, odorless gas that seeps into buildings and homes. Long-term or heavy exposure to radon gas is associated with lung cancer risk. The risk is compounded in those who smoke.

Air pollutants, such as by-products from the combustion of diesel and other fossil fuels, are linked to lung cancer. Some people living outside of the US have an increased risk of lung cancer because of exposure to arsenic in drinking water.

Genetics and Family History

Some genetic risks are inherited, while others develop over time. Genetic make-up can influence risk by:

  • Making it more difficult to break down carcinogens in the body
  • Making the lungs more vulnerable to the actions of carcinogens
  • Having cells that do not have a mechanism to keep them from multiplying in a controlled manner (like brakes on a car)
  • Having cells that have a mechanism that accelerates cellular growth beyond the normal rate (like a gas pedal on a car)
  • Missing or have a specific gene that causes these changes

People who have close family members, like parents, siblings, children, or other relatives, have a higher risk of lung cancer. The association is strongest in relatives who developed lung cancer at 60 years of age or younger.

Medical Conditions or Treatments

Certain medical conditions and/or treatments may increase the risk of lung cancer. Inflammation, irritation, and scarring increase cell turnover which increases the chance for abnormal growth. Conditions associated with an increased risk include:

  • Lung diseases, such as chronic obstructive pulmonary disease (COPD) and tuberculosis (TB).
  • HIV infection suppresses the body's immune system and causes lung diseases like pneumonia.
  • Radiation therapy—Previous treatment for lung or breast cancer, for example, expose the lungs to direct radiation.

Revision Information

  • Lung cancer (non-small cell). American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003115-pdf.pdf. Accessed July 12, 2016.

  • Lung cancer (small cell). American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003116-pdf.pdf. Accessed July 12, 2016.

  • Non-small cell lung cancer. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated January 25, 2016. Accessed July 12, 2016.

  • Small cell lung cancer. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated October 15, 2015. Accessed July 12, 2016.

  • What causes lung cancer? American Lung Association website. Available at: http://www.lung.org/lung-health-and-diseases/lung-disease-lookup/lung-cancer/symptoms-causes-and-risk-factors/what-causes-lung-cancer.html. Accessed July 12, 2016.

  • 10/19/2015 DynaMed Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Silverberg MJ, Lau B, Achenbach CJ, et al. Cumulative incidence of cancer among persons with HIV in North America: a cohort study. Ann Intern Med. 2015;163(7):507-518.