Scientists recently said they have identified the mechanism by which air pollution causes lung cancer in non-smokers, a finding one expert hailed as “an important step for science and society.”
The research illustrated the health risk posed by the tiny particles produced by combustion fossil fuels, sparking new calls for more urgent action to combat climate change. It could also pave the way for a new field of cancer prevention, according to Charles Swanton of the Francis Crick Institute in the UK.
Swanton presented the research at the European Society of Medical Oncology Annual Conference in Paris. For a long time it was considered that pollution air is linked to an increased risk of lung cancer in people who have never smoked, Science Alert compliant.
“But we didn’t really know if pollution directly causes lung cancer,” Swanton told AFP.
How lung cancer occurs
Exposure to carcinogens, such as those from cigarette smoke or pollution, has traditionally been believed to cause DNA mutations which then become cancer. But there was an “inconvenient truth” about that model, Swanton said: Previous research had shown that DNA mutations can be present without causing cancer and that most environmental carcinogens do not cause the mutations.
His study proposes another model. The research team from the Francis Crick Institute and University College London analyzed the health data of over 460,000 people in England, South Korea and Taiwan. They found that exposure to tiny PM2.5 pollution particles, less than 2.5 microns in length, led to an increased risk of mutations in the EGFR gene.
In laboratory studies in mice, the team showed that the particles caused changes in the EGFR gene and KRAS gene, both of which have been linked to lung cancer. Finally, they analyzed nearly 250 human lung tissue samples that had never been exposed to carcinogens through smoking or pollution loud.
Even though the lungs were healthy, they found DNA mutations in 18% of the EGFR genes and 33% of the KRAS genes.
“They just sit there,” Swanton said, adding that the mutations seem to increase with age.
“By themselves, they’re probably not enough to drive cancer,” he said.
But when a cell is exposed to pollution, it can trigger a “wound healing response” that causes inflammation, Swanton said. And if that cell “carries a mutation, then it will form cancer,” he added.
“We have provided a biological mechanism behind what was previously a conundrum,” he said.
–
