Some smokers might not get lung cancer, as researchers report why. A new study conducted by scientists shows that some smokers’ DNA may also be why they don’t get lung cancer. According to the researchers, the genes in these people have the ability to help limit mutations or changes, to DNA which might turn cells malignant and make them grow into tumors.
Lung cancer is the most common cancer death in men and women. But this wasn't always the case. Lung cancer was rare prior to the widespread use of mechanical cigarette rollers. And Today, Lung cancer deaths are caused by smoking nearly 9 out of 10, while radon gas, pollution, and other things play a smaller role. Newly developed drugs provide are a new hope for those diagnosed today.
Scientists have long suspected that smoking leads to lung cancer by triggering DNA mutations in healthy cells. But it was hard for them to identify the mutations in healthy cells that might help predict future cancer risk, Jan Vijg, Ph.D., a senior author of the study and researcher at the University School of Medicine in Shanghai, China, said in a statement. His team used a process called single-cell whole-genome sequencing to examine cells lining the lungs of 19 smokers and 14 non-smokers ranging in age between their pre-teens to their mid-80s. The cells came from patients who had tissue samples collected from their lungs during diagnostic testing unrelated to cancer. The scientists reported their findings in Nature Genetics.
The researchers looked at the cell lining specifically because these cells can survive years of aging and smoking and build up mutations over time in a human body.
"Of all the lung cell types, these are among the most likely to become cancerous," says Simon Spivack, MD, a senior author of the study and professor at the Albert Einstein College of Medicine in New York City. Smokers had far more gene mutations that can cause lung cancer than non-smokers’ natural gene mutations, the analysis found.
"These findings confirm that lung cancer risk is increasing due to smoking. And it increases the frequency of mutations, as previously hypothesized," says Spivack. "This can likely be one of the reasons why so few non-smokers get lung cancer, while 10 to 20 percent of lifelong smokers do."
Among the lifelong smokers, they had smoked a maximum of 116 so-called pack-years. Smoking one pack a day for a year is the equivalent of one pack-year. The number of mutations detected in smokers' lung cells increased in direct proportion to the number of pack-years they smoked.
But after 23 pack-years, no more additional mutations of lung cells in smokers were found, as the researchers report that some people’s genes might more likely fight mutations.
"The heaviest smokers didn't have the highest mutation," says Spivack. "Our findings suggest that these individuals may have survived for so long in spite of their heavy smoking is because they managed to suppress further mutation accumulation."
Doctors might one day find this research useful to help come up with possible better ways to screen for lung cancer and treat the disease, but it's still a long way off. Many lab tests and vast studies will be needed to better pinpoint which smokers might be more prone to lung cancer and why in the future.
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