It is well known that mutations in the BRCA genes increase the risk of female breast and ovarian cancers. But for the first time, researchers from The Institute of Cancer Research in the UK have discovered a link between smokers with a BRCA2 gene mutation and increased risk of lung cancer.
According to the American Cancer Society, approximately 224,201 Americans will receive a lung cancer diagnosis this year.
It is common knowledge that smoking is the leading risk factor for lung cancer, causing at least 80% of deaths from the disease.
But the researchers of this latest study, led by Richard Houlston, professor of molecular population and genetics at The Institute of Cancer Research (ICR), say past studies have indicated that genetic factors may also increase lung cancer risk.
To investigate further, the research team compared the DNA of 11,348 European individuals who had lung cancer with the DNA of 15,861 Europeans who were free of the disease.
Their findings, recently published in the journal Nature Genetics, revealed that smokers who had mutations in the BRCA2 gene had a 25% chance of developing lung cancer during their lifetime. Smokers in general have around a 13-15% chance of lung cancer, so the study results show that a BRCA2 gene mutation can increase lung cancer risk even further.
The team found that this association was most prominent among study participants who had squamous cell lung cancer – the most common subtype of the disease.
In addition, they discovered that individuals with this subtype had a mutation in another gene, called CHEK2. This gene usually stops cell division following DNA damage.
According to the researchers, the study results indicate that patients with squamous cell lung cancer may benefit from drugs that are already known to be effective in cancer patients with BRCA mutations.
For example, the investigators note that in clinical trials, poly ADP ribose polymerase (PARP) inhibitors have proved successful in breast and ovarian cancer patients with BRCA mutations. But the researchers point out that as yet, it is unclear as to whether such drugs would work for lung cancer patients.
Commenting on the team’s findings, Prof. Houlston says:
“Our study showed that mutations to two genes, BRCA2 and CHEK2, have a very large effect on lung cancer risk in the context of smoking. Mutated BRCA2 in particular seems to increase risk by around 1.8 times.
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.”
Earlier this year, Medical News Today reported on a study that revealed even thirdhand smoke – exposure to the toxic compounds of tobacco smoke from dust or surfaces in a room where a person has smoked previously – may damage DNA and increase cancer risk.
A more recent study, conducted by researchers from the University of Manchester in the UK, found that smoking and passive smoking may increase the risk of hearing loss.