A new study published in Nature reveals that air pollution and other environmental factors are causing genetic mutations that lead to lung cancer in people who have never smoked. This research helps explain a troubling trend: as smoking rates drop worldwide, lung cancer in never-smokers is becoming more common, especially among women and people of Asian ancestry.
Scientists from the University of California San Diego and the National Cancer Institute studied lung tumors from 871 never-smokers across 28 regions in Africa, Asia, Europe, and North America. They used advanced genetic testing to find specific patterns of DNA damage, like molecular fingerprints that show what caused the cancer.
The researchers discovered that people living in more polluted areas had significantly more mutations in their lung tumors. Those exposed to higher pollution levels had nearly four times more mutations linked to tobacco damage and 76% more mutations related to aging. The study showed a clear pattern: the more pollution someone breathed, the more genetic damage appeared in their tumors.
Surprisingly, secondhand smoke showed much weaker effects than air pollution. While secondhand smoke is still dangerous, it caused far fewer genetic changes than breathing polluted air.
The study also found that certain traditional Chinese herbal medicines containing aristolochic acid may cause lung cancer when inhaled. This chemical was previously known to cause other cancers when eaten, but this is the first evidence it might affect the lungs through breathing.
Most intriguingly, researchers discovered a completely new type of genetic damage that appears in most never-smokers with lung cancer but not in smokers. They don’t yet know what causes this pattern, opening up new areas for research.
This research is crucial because it provides the first genetic proof that environmental factors beyond smoking cause lung cancer.