Most smokers have a 15 percent chance of developing lung cancer at some point over the course of their lives — that’s a much greater risk than someone who never smoked. But researchers from The Institute of Cancer Research in London have found that two genetic mutations, which are found in about two percent of people of European descent, can raise a smoker’s risk of developing lung cancer to about 25 percent over the course of his or her life.
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The discovery means that smokers, and former smokers, may benefit from genetic testing and regular cancer screenings if they’re found to belong to higher-risk group.
Smoking and Lung Cancer Risk
The damaging health effects of smoking cigarettes have been well-documented. Smoking harms every organ of the body and is responsible for 90 percent of lung cancer deaths each year. Even after you quit smoking, your risk of lung cancer remains high. A former smoker’s lung cancer risk does not return to normal until at least 15 years after he or she puts out that last cigarette. Fifty percent of lung cancers occur in former smokers. Specific lung cancer treatments may be best for smokers and former smokers who are found to have developed genetically-influenced lung cancer.
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Lung Cancer Gene Discovered
In a report recently published in the journal Nature Genetics, researchers at The Institute of Cancer Research in London compared the genetic information of 11,348 Europeans with lung cancer to that of 15,861 Europeans without lung cancer, in order to pinpoint any specific differences in their DNA. While the researchers weren’t actually looking for mutations in the BRCA2 gene, which has already been linked to ovarian, breast and other cancers, they did find that smokers who developed lung cancer were also likely to share this genetic mutation. The link between the BRCA2 mutation and lung cancer was strongest in patients suffering from squamous cell lung cancer, the most common type. The researchers also found a strong link between squamous cell lung cancer and a defect in the CHEK2 gene.
While smokers in general have about a 15 percent chance of developing lung cancer at some point in their lifetimes, the researchers found that one or both of these genetic mutations increase a smoker’s risk of lung cancer by 1.8 times. One in four smokers with the BRCA2 and CHEK2 mutations will develop lung cancer.
New Treatment Approaches for Lung Cancer
The researchers believe that this discovery could herald important new preventative care and treatment approaches for smokers who develop lung cancer. The BRCA2 and CHEK2 genes are present in about two percent of people of European descent; genetic testing could be used to determine which smokers actually carry these dangerous genetic mutations. Annual cancer screenings for smokers over the age of 55 are already recommended by the U.S. Preventive Services Task Force, and are capable of preventing as many as 20 percent of lung cancer deaths among this age group. Yearly cancer screenings for smokers who are found to carry the BRCA2 or CHEK2 genes could save just as many lives.
The results of the study also suggest that the same drug therapies designed to be effective in BRCA2-influenced breast and ovarian cancers might also be especially useful for treating lung cancers linked to this genetic mutation. A class of drugs known as PARP inhibitors has shown promise in clinical trials for the treatment of ovarian and breast cancer. Researchers have yet to investigate the potential of these drugs for treating genetically-influenced lung cancer.
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Experts also underscore the importance of encouraging smokers who carry the BRCA2 and CHEK2 mutations to quit smoking altogether. The news that one is particularly prone to developing lung cancer from smoking might provide the extra incentive necessary to quit, with the help of nicotine replacement therapy or drugs like varenicline (Chantix), if necessary. Smokers who are found to carry the genetic mutation may also want to warn their children, siblings and other relatives that they might potentially have an increased risk of lung cancer, although those who carry the gene but never smoke do not have an increased risk of lung cancer.
Researchers in London have determined that genetic mutations on the BRCA2 and CHEK2 genes can almost double a smoker’s lifetime risk of lung cancer. Genetic testing and cancer screenings can save the lives of smokers who carry the lung cancer gene, and these smokers should be especially encouraged to quit. Never smoking is still the best way to avoid lung cancer.
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