Researchers have identified chemical changes in the blood that may help explain how air pollution leads to lung cancer, according to a new study.
Air pollution is already known to be a major cause of lung cancer, but scientists have struggled to understand exactly how dirty air triggers the disease inside the body. A team from Emory University, the American Cancer Society and international collaborators set out to find the missing link by studying blood samples taken from more than 1,300 people years before any of them were diagnosed with cancer.
The participants, drawn from two long-running US cancer studies, gave blood samples while still healthy. Researchers later measured over 1,100 different chemicals, known as metabolites, circulating in that blood, and compared them against estimated pollution levels, including soot-like particulate matter, ozone and traffic fumes, near each person’s home at the time.
Some participants went on to develop lung cancer years later. By comparing their blood chemistry with that of people who stayed cancer-free, the team pinpointed eight specific metabolites that were linked to both pollution exposure and future lung cancer risk. Four of these appeared to actively mediate the connection between certain pollutants and the disease.
Several of the flagged chemicals are tied to the body’s antioxidant defences and inflammation response, suggesting pollution may drive cancer partly by overwhelming the body’s ability to neutralise harmful oxidative damage. Others were linked to how the body processes furan, a toxic byproduct of burning fuel, wood or tobacco, hinting that traffic and industrial emissions may cause similar internal damage to smoking.
Importantly, the results held up even after accounting for smoking status, meaning the effects were not simply explained by cigarette use, though the researchers say smoking likely still plays some role in these pathways.
The scientists describe their findings as ‘hypothesis-generating’ rather than final proof, and caution that the study mostly involved older, white participants, meaning further research is needed in more diverse populations. Still, they say identifying these biological warning signs could eventually help doctors flag people at higher risk from air pollution before cancer develops, and could point toward new targets for prevention.
‘These findings suggest that air pollution may promote lung cancer partly through metabolic pathways related to inflammatory and oxidative processes,’ the authors wrote, adding that the work lays groundwork for future studies into how everyday air quality affects long-term health.
The full research can be read here.
Photo: National Cancer Institute
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