A new study suggests that some smokers may be immune to lung cancer due to their DNA.
According to the researchers, these people have genes that help limit DNA mutations that would turn cells malignant and cause them to grow into tumors.
Smoking, scientists have long suspected, causes lung cancer by causing DNA mutations in healthy cells. However, it was difficult for them to identify the mutations in healthy cells that could help predict future cancer risk, according to Jan Vijg, PhD, a senior author of the study and researcher at the University School of Medicine in Shanghai, China.
The study discovered that smokers had far more gene mutations that can lead to lung cancer than nonsmokers.
“This experimentally confirms, as previously hypothesised, that smoking increases lung cancer risk by increasing the frequency of mutations,” says Spivack. “This is probably one of the reasons why so few nonsmokers develop lung cancer while 10 to 20% of lifelong smokers do.”
People had smoked a total of 116 so-called pack-years among smokers. A pack-year is the equivalent of smoking one pack of cigarettes every day for a year. The number of mutations found in smokers’ lung cells increased proportionally to the number of pack-years smoked.
However, after 23 pack-years, smokers’ lung cells did not appear to add more mutations, suggesting that some people’s genes may make them more likely to fight mutations.
According to Spivack, “the heaviest smokers did not have the highest mutation burden.” “Our findings suggest that these people may have survived so long despite heavy smoking because they were able to suppress further mutation accumulation.”
While these findings may one day help doctors develop better ways to screen for and treat lung cancer, that is still a long way off. Many more lab tests and larger studies will be required to better determine which smokers are more likely to develop lung cancer and why.