Genetic Link to Lung Cancer Risk in Asian WomenNov 12, 2012
International researchers have linked 3 genetic regions to an increased risk for lung cancer among Asian women who have never smoked. The finding adds to growing evidence that lung cancer risk among nonsmokers may be associated with genetic factors that distinguish it from lung cancer in smokers.
Co-author Stephen J. Chanock, MD, said, “This is an exciting and important paper because it represents the next generation of gene studies better suited to account for environmental exposure.”
Historically, the majority of lung cancer cases in Eastern Asian women have been found among women who never smoked, according to the National Cancer Institute (NCI) in the United States. Secondhand smoke and exhaust from indoor cooking explain only a small portion of the cases. Researchers from the NCI partnered with researchers from several other countries to analyze data from 14 studies that included about 14,000 women from China, Japan, Singapore, Taiwan, Hong Kong, and Korea. They published their findings online Nov. 11, 2012 in Nature Genetics.
The researchers found that variations at 3 locations in the genome were associated with lung cancer in nonsmoking Asian women. “Our study provides strong evidence that common inherited genetic variants contribute to an increased risk of lung cancer among Asian women who have never smoked,” said co-author Nathaniel Rothman, MD. “These variants may also increase lung cancer risk associated with environmental factors, such as environmental tobacco smoke.”
The researchers have plans to study the genetic variations in other populations of people.
In the US
Every year, 16,000 to 24,000 nonsmoking Americans die of lung cancer. If lung cancer in nonsmokers had its own category separate from lung cancer in smokers, it would rank among the top 10 fatal cancers in the US.
The leading cause of lung cancer in nonsmokers is exposure to radon gas, according to the US Environmental Protection Agency (EPA). Radon accounts for about 20,000 deaths from lung cancer each year. It occurs naturally outdoors in harmless amounts, but sometimes becomes concentrated in homes built on soil with natural uranium deposits. Studies have found that the risk of lung cancer is higher in those who have lived for many years in a radon-contaminated house.
Secondhand smoke is responsible for an estimated 3,400 lung cancer deaths among nonsmoking adults in the US each year. Laws that prohibit smoking in public places and create smoke-free environments have been effective in reducing this danger.
Other risk factors for lung cancer in nonsmokers include exposure to carcinogens like asbestos and diesel exhaust, which often occurs in the workplace, and indoor and outdoor air pollution.
Even so, nonsmokers have already eliminated their greatest risk factor for lung cancer. Male smokers are about 23 times more likely and female smokers about 13 times more likely to get lung cancer than nonsmokers.
Gene studies like the one done in Asia could help explain why some non-smokers develop lung cancer, and potentially help researchers find more effective ways to treat or even prevent it.
Genome-wide association analysis identifies new lung cancer susceptibility loci in never-smoking women in Asia. Published online Nov. 11, 2012 in Nature Genetics. First author: Qing Lan, MD, PhD, National Institutes of Health.