Causes and Risk Factors

Although there are a number of potential causes and risk factors for lung cancer, the most common by far is smoking. The risk of developing lung cancer from smoking depends on how much and how long you have smoked. The more and longer you have smoked, the higher the likelihood of developing lung cancer.

Other risk factors include:

  • Exposure to asbestos or the radioactive gas radon
  • Exposure to second-hand smoke
  • Having another lung disease, such as tuberculosis
  • Having a family or personal history of lung cancer
  • Exposure to certain air pollutants
  • Exposure to coal dust

These additional risk factors increase a smoker's risk of developing lung cancer.

The respiratory system has natural defenses against toxins and irritants. The nose is the first defense, acting as a filter and preventing certain pollutants from entering the lungs.

Those pollutants that do get into the lungs are trapped in a thin layer of sputum, or mucus, lining the breathing tubes of the lungs. Thousands of tiny hairs called cilia move the "dirty" mucus from the lungs toward the throat, where the mucus is then discarded by swallowing or spitting.

The toxic chemicals in cigarettes damage the cells lining the lungs and the cilia. Without cilia to remove toxin-filled mucus, the cancer-causing chemicals are trapped in the lungs. Smoking also damages the alveoli (air sacs) preventing the lungs from properly absorbing oxygen and exhaling carbon dioxide.

Repeatedly exposing the lungs to the chemicals found in cigarettes causes significant inflammation that leads to the development of lung cancer. Although all smokers are at risk for developing lung cancer, heavy smokers (15 or more cigarettes a day) have the greatest risk.

Smoking cessation is associated with significant health benefits for both male and female smokers of all ages. Studies have demonstrated a reduced risk of developing lung cancer in smokers who have quit.
Estimates of the extent of risk reduction over time vary from 20 to 90 percent, depending upon the duration of abstinence, with a progressive decline in risk associated with an increasing duration of abstinence.

It is also known that quitting smoking even a few weeks before a lung operation results in significant benefits during recovery after lung surgery. For this reason, Swedish lung surgeons strongly encourage all patients to stop smoking immediately upon meeting them — for their own benefit with respect to recovery and survival after surgery.

Resources to Quit Smoking

Swedish offers a smoking cessation program that lasts for eight weeks and provides participants with education and coaching to help them successfully stop smoking. The program involves a comprehensive approach to care. It focuses on not only the medical issues related to smoking, but also on the emotional and stress-management issues that help people to become successful non-smokers for life.

Learn more about Swedish's smoking cessation program (PDF), including the five keys for quitting smoking.

Other available resources to learn how to quit smoking:

  • The Tobacco Quit Line offered by the Washington State Department of Health. For more information, visit www.quitline.com or call 1-800-QUIT-NOW.

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