Inflammatory Genes Raise Lung Cancer Risk

2 variants alter immune system's response to infection, cell damage, study finds

WEDNESDAY, July 11, 2007 (HealthDay News) -- Changes in two genes that activate the immune system after tissue damage may increase lung cancer risk, researchers report.

The changes were found on the genes for interleukin 1A and 1B, two molecules that immune system cells secrete in response to infection or tissue damage. The changes may cause the body to overproduce the molecules, which could sustain the inflammatory effects of the damage.

Writing in the July issue of Cancer Research, the researchers observed a stronger effect of the genes in heavy tobacco smokers.

"Our findings help explain how heavy smoking, for example, combines with a genetic predisposition to create a besieged environment within the lungs," lead author Dr. Eric Engels, researcher at the Viral Epidemiology Branch of the U.S. National Cancer Institute's Division of Cancer Epidemiology and Genetics, said in a prepared statement. "Essentially, sustained inflammation alters the microenvironment of the lung tissue, damaging cells and altering DNA."

The study is the first to pinpoint the mechanism by which damage to the lung might cause an inflammatory response from the immune system, leading to cancer. Inflammation is a normal part of the immune system's response to the effects of infection and cell damage, but the researchers argue that prolonged inflammation could increase the risk of lung cancer.

The team examined differences in genes related to inflammation among more than 1,500 lung cancer patients and 1,700 healthy adults. More than 80 percent of the lung cancer patients were former or current smokers.

The researchers then analyzed 59 variations on 37 inflammation-related genes. They found variants in the genes for interleukin 1A and 1B more frequently in patients with lung cancer, especially among heavy smokers.

More Americans die from lung cancer each year than any other type of cancer. In 2003, the most recent year for which data is available, 105,508 men and 84,789 women were diagnosed with lung cancer, while 89,906 men and 68,084 women died from the disease.

More information

To learn about lung cancer, visit the Centers for Disease Control and Prevention.

SOURCE: American Association for Cancer Research, news release, July 3, 2007
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