Research has demonstrated the health risk posed by tiny particles produced by burning fossil fuels, sparking 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 UK’s Francis Crick Institute. Swanton presented the research, which has not yet been published in a peer-reviewed journal, at the European Society of Medical Oncology’s annual meeting in Paris on Saturday. Air pollution has long been thought to be linked to a higher risk of lung cancer in people who have never smoked. Commuters make their way through smog in New Delhi on November 20, 2021 [File: Prakash Singh/AFP] “But we didn’t really know if the pollution directly caused lung cancer – or how,” Swanton told the AFP news agency. It has traditionally been believed that exposure to carcinogens, such as those in cigarette smoke or pollution, causes DNA mutations that then become cancer. But there was an “inconvenient truth” to that model, Swanton said: previous research has shown that DNA mutations can exist without causing cancer — and that most environmental carcinogens don’t cause the mutations. His study suggests a different model.
A future cancer pill?
The research team from the Francis Crick Institute and University College London analyzed the health data of more than 460,000 people in England, South Korea and Taiwan. They found that exposure to tiny PM2.5 pollution particles – which are less than 2.5 micrometers (small) in diameter – led to an increased risk of mutations in the epidermal growth factor receptor (EGFR) gene. In laboratory studies in mice, the team showed that the particles caused changes in the EGFR gene as well as the Kirsten rat sarcoma virus (KRAS) gene, both of which have been linked to lung cancer. Finally, they analyzed nearly 250 samples of human lung tissue that had never been exposed to carcinogens from smoking or heavy pollution. Even though the lungs were healthy, they found DNA mutations in 18 percent of the EGFR genes and 33 percent of the KRAS genes. People enjoy a day out in Primrose Hill as a high air pollution warning is issued for London on March 24, 2022 [File: Justin Tallis/AFP] “They’re just sitting there,” Swanton said, adding that mutations appear 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 “harbors a mutation, then it will form cancer,” he added. “We have provided a biological mechanism behind what was previously an enigma,” he said. In another experiment in mice, the researchers showed that an antibody could block the mediator – called interleukin 1 beta – that triggers inflammation, preventing cancer from starting in the first place. Swanton said he hopes the finding will “provide fertile ground for a future of molecular cancer prevention, where we can offer people a pill, perhaps every day, to reduce their cancer risk.” A general view of Milad Tower after the increase in air pollution in Tehran, Iran on November 24, 2021 [File: Majid Asgaripour/WANA via Reuters]
‘Revolutionary’
Suzette Delaloge, who heads the cancer prevention program at France’s Gustave Roussy institute, said the research was “quite revolutionary, because we had practically no previous demonstration of this alternative way of cancer formation”. “The study is a very important step for science – and for society as well, I hope,” he told AFP. “This opens a huge door, both for knowledge, but also for new ways to prevent” the cancer from developing, said Delaloge, who was not involved in the research but discussed it at the conference on Saturday. “This level of protest must force the authorities to act on an international scale.” Tony Mok, an oncologist at the Chinese University of Hong Kong, called the research “exciting”. “It means we can ask whether, in the future, it will be possible to use lung scans to look for precancerous lesions in the lungs and try to reverse them with drugs such as interleukin-1 beta blockers,” he said. Swanton called air pollution a “hidden killer,” pointing to research that estimates it is linked to the deaths of more than eight million people a year — nearly the same number caused by tobacco. A general view of a section of the Kathmandu Valley during a smoggy day as air quality reaches hazardous levels, Nepal, April 6, 2021 [File: Navesh Chitrakar/Reuters] Other research has linked PM2.5 to 250,000 deaths per year from lung cancer alone. “You and I have a choice about whether we smoke or not, but we don’t have a choice about the air we breathe,” said Swanton, who is also the chief clinician at Cancer Research UK, which was the main funder of the research. . “Given that probably five times as many people are exposed to unhealthy levels of pollution from secondhand smoke, you can see that this is a very significant global problem,” he added. “We can only address this if we recognize the really close links between climate health and human health.”
