London, SANA- A new study published in Nature magazine reveals that air pollution, traditional herbal medicines and other environmental exposures are linked to genetic mutations that may contribute to the development of lung cancer in people with no or hardly any history of smoking.
Lung cancer has long been thought of as a smoker’s disease but as tobacco use has declined in many parts of the world, a troubling trend has emerged: lung cancer in people who have never smoked is proportionally on the rise.
Moreover, this form of cancer disproportionately affects women, particularly those of Asian ancestry, and tends to be more prevalent in East Asian than in Western nations.
Now, a study uncovered compelling genomic evidence that points to air pollution—and other environmental exposures—as a potential major factor behind this growing public health concern. The study was jointly led by researchers at the University of California San Diego and the National Cancer Institute (NCI), part of the National Institutes of Health (NIH).
The team analyzed lung tumors from 871 never-smokers living in 28 regions with different levels of air pollution across Africa, Asia, Europe and North America. Using whole-genome sequencing, the researchers identified distinct patterns of DNA mutations—known as mutational signatures—that act like molecular fingerprints of past exposures.
By combining these genomic data with pollution estimates based on satellite and ground-level measurements of fine particulate matter, the researchers were able to estimate individuals’ long-term exposure to air pollution. They found that never-smokers living in more polluted environments had significantly more mutations in their lung tumors, particularly driver mutations—which directly promote cancer development—and mutational signatures linked to cancer—which serve as a record of all past mutagenic exposures. For example, these individuals had a 3.9-fold increase in a mutational signature linked to tobacco smoking and a 76% increase in another signature linked to aging.
“We’re seeing this problematic trend that never-smokers are increasingly getting lung cancer, but we haven’t understood why,” said study co-senior author Ludmil Alexandrov, professor of bioengineering and cellular and molecular medicine at UC San Diego, and member of UC San Diego Moores Cancer Center.
“Our research shows that air pollution is strongly associated with the same types of DNA mutations we typically associate with smoking.” He added.
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