1 in 4 Smokers With Gene Defect May Get Lung Cancer

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SUNDAY, June 1, 2014 (HealthDay News) -- Up to one in four smokers with a particular genetic defect will develop lung cancer, researchers report.

"Smokers in general have nearly a 15 percent chance of developing lung cancer, far higher than in nonsmokers. Our results show that some smokers with BRCA2 mutations are at an enormous risk of lung cancer -- somewhere in the region of 25 percent over their lifetime," said study leader Richard Houlston. He's a professor of molecular and population genetics at the Institute of Cancer Research in the United Kingdom.

"Lung cancer claims more than a million lives a year worldwide," he said in an institute news release. "We know that the single biggest thing we can do to reduce death rates is to persuade people not to smoke, and our new findings make plain that this is even more critical in people with an underlying genetic risk."

The link between lung cancer and the defect in the BRCA2 gene was discovered by analyzing the DNA of more than 11,000 Europeans with lung cancer and almost 16,000 without the disease.

This particular BRCA2 defect -- already known to increase the risk of breast cancer -- occurs in about 2 percent of people and almost doubles the risk of lung cancer, according to the study published online June 1 in the journal Nature Genetics.

The link between the BRCA2 defect and lung cancer was particularly strong among patients with the most common type of lung cancer -- squamous cell lung cancer. The researchers also identified a link between squamous cell lung cancer and a defect in another gene called CHEK2, which normally prevents cells from dividing when they have damaged DNA.

The study findings suggest that drugs designed to target BRCA mutations might benefit patients with squamous cell lung cancer. A class of drugs called PARP inhibitors have shown promise in clinical trials involving breast and ovarian cancer patients with BRCA mutations, but it's not known if these drugs could help lung cancer patients, the study authors said.

It's also important to note that while the researchers found a strong link between a defect in the BRCA2 gene and lung cancer, the study didn't prove that the genetic defect was responsible for causing lung cancer.

More information

The U.S. Centers for Disease Control and Prevention outlines lung cancer risk factors.