Lung Cancer Genetics

Lung cancer is a respiratory disease in which cells in the lungs grow and reproduce uncontrollably. The American Cancer Society has reported that lung cancer is the leading cancerous cause of death in men and the second leading cause of cancer death in women in the United States.

Roughly 975,000 men and 376,000 women die annually from lung cancer. Smoking increases the risk of getting lung cancer, but nonsmokers can also develop the disease.

Recent research has found that two genes are present in smokers and nonsmokers who have been diagnosed with lung cancer. This would help explain why some nonsmokers contract lung cancer, and why some smokers do not.

Causes of Lung Cancer

Several causes of cancer exist, but the single most common cause is long-term exposure to tobacco smoke. Smoking statistics vary, but about 87 percent of lung cancer cases in the United States can be directly attributed to smoking.

The length of time and rate at which a person smokes affects their chance of developing lung cancer. When a person stops smoking, he decreases his risk of developing lung cancer. After a person quits smoking, the body can begin to repair and clean itself.

Nonsmokers make up between 10 and 20 percent of all lung cancer cases. The causes in nonsmokers include:

  • air pollution, including secondhand smoke
  • asbestos
  • genetic factors
  • radon gas
  • viral infections.

Nonsmokers with lung cancer have a better prognosis than smokers, meaning they are more likely to survive the disease.

Lung Cancer Treatment and Prognosis

The best way to prevent lung cancer is to avoid tobacco smoke and other carcinogenic substances. Treatment and prognosis of lung cancer depends on the type of cancer, the stage (how long and how much it has spread in the lungs and other organs) and the patient’s performance status.

Two types of lung cancer exist: small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). Each type requires different treatment. SCLC responds to chemotherapy or radiation. NSCLC sometimes requires surgery. With treatment, the five-year survival rate is 14 percent.

The Genetics of Lung Cancer: Recent Research

Approximately 80 percent of smokers do not develop lung cancer. Researchers have recently made discoveries that may help determine why some people are more susceptible to contracting lung cancer. Two different variations of a single nucleotide in two different genes may raise the risk of lung cancer.

Both of these genes code for nicotinic acetylcholine receptors. These receptors are cell-surface proteins that bind to nicotine molecules. The complex of a nicotine molecule bound to the receptor triggers a cascade of effects. Cells in the lungs begin to grow rapidly and uncontrollably. This triggers the growth of feeder blood vessels. This, in turn, creates a perfect environment for cancer tumors.

Researchers found that individuals with two copies of the gene had an 81 percent higher risk of developing lung cancer. Those with only one copy were 28 percent more likely. One study found that nonsmokers with copies of this gene were also at slightly higher risk for developing lung cancer, which could explain some incidences of lung cancer in nonsmokers with otherwise healthy lungs.

Obtaining knowledge about a patient’s genetic variations could affect the treatment of lung cancer. Some people may require behavioral modification. Others may be prescribed nicotine blockers. Smokers must understand that if they do not have the variation in the genes, they can still get lung cancer.

Preventing Lung Cancer

If you find through a genetic test that you or your child has a high risk for lung cancer, remember that it does not mean that wither of you will actually develop the disease. You can take steps to prevent the onset of lung cancer:

  • be aware of any toxins in your workplace, like coal products or mustard gas, and limit your exposure
  • eat lots of fruits and vegetables, which can help protect your DNA and repair damaged cells
  • have your home tested for radon
  • keep away from secondhand smoke
  • stop smoking immediately if you are a smoker.

Resources

Park, A. (2008). Lung cancer gene identified. Retrieved November 19, 2008, from the Time Web site: http://www.time.com/time/health/article/0,8599,1727161,00.html.

Reuters (2008). Two lung cancer genes identified. Retrieved November 19, 2008, from the MSNBC Web site: http://www.msnbc.msn.com/id/27503938/.