(RxWiki News) After decades of public health initiatives, it’s no secret that smoking is bad for your health and can ultimately cause lung cancer.
But a single genetic marker might nearly double the odds that a smoker will develop the often fatal condition.
A large global study led by British scientists suggested that smokers with a genetic mutation found in around 2 percent of the overall population may have a 25 percent chance of getting lung cancer in their lifetime.
"Discuss options for how to quit smoking with your doctor."
Richard Houlston, MD, PhD, professor of molecular and population genetics at the Institute of Cancer Research in London, co-led this study, which received contributions from more than 50 scientists around the world.
Drawing on voluminous genetic data, the team analyzed the link between the gene BRCA2 and lung cancer risk.
BRCA2 has been shown to increase the risk for breast, ovarian and other cancers.
To look for differences in the BRCA2 gene, Dr. Houlston and colleagues compared DNA of 11,348 Europeans with lung cancer and 15,861 without lung cancer.
These researchers found that a particular mutation to BRCA2, which is found in about 2 percent of people, increased the risk of developing lung cancer by around 1.8 times.
Smokers already have about a 13 percent chance of developing lung cancer regardless of genetics. Based on the new findings, one in four smokers with the BRCA2 defect would develop lung cancer.
In Great Britain, there are 10 million adult smokers, according to the authors of this study. Using the 2 percent BRCA2 figure, that means 200,000 of those smokers have a one in four chance of developing lung cancer.
This research also uncovered an even stronger link between the gene defect and squamous cell lung cancer, the most common subtype of lung cancer.
Squamous cell lung cancer accounts for 25 to 30 percent of all lung cancer cases and is often linked to a history of smoking, according to the American Cancer Society.
Dr. Houlston said in a prepared statement that smokers with the BRCA2 mutation “are at an enormous risk of lung cancer — somewhere in the region of 25 percent over their lifetime.”
He added, "Lung cancer claims more than a million lives a year worldwide and is by far the biggest cancer killer in the UK. 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 authors concluded that patients with squamous cell lung cancer could benefit from treatment specifically designed to be effective in cancers with the BRCA2 mutation.
The study was published June 1 in the journal Nature Genetics.
Funding for this study came from the National Institutes of Health in the United States and the Cancer Research Institute in the United Kingdom.
The authors did not report any relevant financial conflicts of interest.