Scientists said Saturday they had identified a mechanism by which air pollution triggers lung cancer in nonsmokers, a finding that one expert hailed as “an important step for science and for society.”

The study reveals the health risks posed by tiny particles produced by burning fossil fuels and has sparked a new call for more urgent action to combat climate change.

It could also pave the way for new areas of cancer prevention, according to Charles Swanton of the Francis Crick Institute in the UK.

Dr. Swanton presented the study, which has not yet been published in a peer-reviewed journal, at the European Society of Clinical Oncology’s annual meeting in Paris.

Air pollution has long been associated with an increased risk of lung cancer in never-smokers.

“But we really didn’t know if the pollution was directly causing lung cancer or how it was caused,” Swanton told AFP.

It has traditionally been thought that exposure to carcinogens in cigarette smoke and air pollution causes DNA mutations that lead to cancer.

But there was an “inconvenient truth” in the model, Swanton said. Previous studies have shown that DNA mutations can exist without causing cancer, and most environmental carcinogens do not cause mutations.

In his research another model is proposed.

Anticancer drug of the future?

Researchers from the Francis Crick Institute and University College London analyzed health data from over 460,000 people in the United Kingdom, South Korea and Taiwan.

They found that exposure to small PM2.5 pollution particles less than 2.5 microns in diameter increased the risk of mutations in the EGFR gene.

In laboratory studies in mice, the researchers showed that the particles caused changes in the EGFR and KRAS genes, both of which are associated with lung cancer.

Finally, they analyzed approximately 250 samples of lung tissue from humans who had never been exposed to carcinogens from smoking or heavy pollution.

Despite lung health, they found DNA mutations in 18% of the EGFR gene and 33% of the KRAS gene.

“They just sit there,” Swanton said, adding that mutations seem to increase with age.

“Alone it’s probably not enough to cause cancer,” he said.

But when cells are exposed to contamination, they can trigger a “wound-healing response” that triggers inflammation, Swanton said.

And if the cell “has a mutation, it forms a cancer,” he added.

“It provided the biological mechanism behind what was previously a mystery,” he said.

In another experiment with mice, the researchers showed that the antibodies could block a mediator called interleukin-1 beta.

Swanton hopes the discovery “provides a fruitful basis for the future of molecular cancer prevention, which could possibly provide people with a pill every day to reduce their risk of cancer.”

“Revolutionary”

Suzette Delaroge, head of the cancer prevention program at the Gustave Roussy Institute in France, said the study was “very revolutionary, because to date there has been virtually no demonstration of this alternative way of forming cancer.” This is because the.

“This research is a very important step for science and an important step for society,” she told AFP.

“This opens a huge door for both knowledge and new ways to prevent cancer from occurring,” said Delaloge, who was not involved in the study but discussed it at a meeting on Saturday.

“Demonstrations of this level must force authorities to act on an international scale.”

Tony Mok, an oncologist at the Chinese University of Hong Kong, called the study “exciting.”

“This may ask whether it will be possible in the future to use lung scans to look for precancerous lesions in the lungs and try to reverse them with drugs such as interleukin-1 beta inhibitors. means

Calling air pollution a “hidden killer,” Swanton points to studies that estimate that air pollution is responsible for more than eight million deaths annually, about the same number as tobacco.

Other studies have linked PM2.5 with 250,000 deaths annually from lung cancer alone.

“You and I can choose whether or not we smoke, but we cannot choose the air we breathe,” said Swanton, who is also the lead clinician at Cancer Research UK, the study’s main funder. .

“Given that perhaps five times more people are exposed to unhealthy levels of pollution than cigarettes, this proves to be a huge global problem.

“We can only work on it if we recognize that there is a really close relationship between climate health and human health.”

© Agence France-Presse