Smokers with Dangerous Gene Defect Have One in Four Chance of Developing Lung Cancer

Environmental influences can play a role in whether or not you develop cancer, but genetics also has a major role. Scientists have found that one in four smokers who carry a defect in the BRCA2 gene will develop lung cancer at some point in their lifetime.

Lung cancer claims more than a million lives a year worldwide. In fact, it's the biggest cancer killer in the UK. That's why it's so important to understand what factors increase the risk of lung cancer.

It turns out that the defect in BRCA2, which is a gene best known for its role in breast cancer, increases the risk of developing lung cancer by about 1.8 times. This means that if a person smokes, they're raising that risk even further if they possess the defect in this gene. In fact, smokers as a group actually have a high lifetime risk of development lung cancer-about 13 percent.

In order to learn what genetics might contribute to the development of lung cancer, the researchers compared the DNA of 11,348 Europeans with lung cancer and 15,861 without lung cancer. They looked for differences at specific points in their DNA. Eventually, they found a link between lung cancer and defective BRCA2.

"Our study showed that mutations in two genes, BRCA2 and CHEK2, have a very large effect on lung cancer risk in the context of smoking," said Richard Houlston, one of the researchers, in a news release. "Mutated BRCA2 in particular seems to increase risk by around 1.8 times. Smokers in general have nearly a 15 percent chance of development lung cancer, far higher than non-smokers. 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."

The findings reveal the importance of not smoking in order to reduce the risk of lung cancer-especially for those that carry a genetic risk.

The findings are published in the journal Nature Genetics.