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A study published on Saturday revealed that some air pollutants are like a “hidden killer” that can cause a number of lung cancers in non-smokers, and reaching their understanding is an “important step for science and society,” according to a group of experts.
Scientists from the Francis Crick Institute and University College London explained that fine particles (less than 2.5 microns, roughly the diameter of a hair), which are considered among the causes of climate change, lead to cancerous changes in the cells of the respiratory system.
Fine particles in exhaust gases, brake dust or fumes from fossil fuels can be likened to a “hidden killer”, said Charles Swanton of the Francis Crick Institute, who presented the results of this research, which has not yet been reviewed by other researchers. During the annual conference of the European Society of Medical Oncology, held in Paris to 13 September.
Recalling that the harm of air pollution has been known for a long time, Professor Swanton noted that scientists were “not sure whether or how this pollution directly causes lung cancer.”
The researchers first studied data on more than 460,000 people from England, South Korea and Taiwan, and showed an association between exposure to increased concentrations of fine particles and an increased risk of lung cancer.
However, the most notable discovery is the understanding of the mechanism by which these pollutants cause lung cancer in non-smokers.
In laboratory studies on mice, the researchers demonstrated that the particles induced changes in two genes, namely epidermal growth factor receptor (EGFR) and Keras (KRAS), which are already linked to lung cancer.
Then the researchers analyzed about 250 samples of healthy human lung tissue that had never been exposed to carcinogens from tobacco or heavy pollution. Mutations in the EGFR gene appeared in 18 percent of the samples, and changes in KRAS in 33 percent of them.
Prof Swanton said: “These mutations may not by themselves be enough to lead to cancer. But when the cell is exposed to contamination, it potentially stimulates some kind of reaction.” He added that “the cell will give rise to cancer” if it “has a mutation.”
Swanton, who heads the study’s main sponsor, Cancer Research UK, said the study was “a decoding of the biological mechanism of what was a mystery.”
It was believed that exposure to cancer-causing factors, such as those resulting from cigarette smoke or pollution, causes genetic mutations in cells, making them tumors and leading to their proliferation.
The director of the Cancer Prevention Program at the Gustave Rossi Sozette Delalog Institute noted that the findings of the study are a “revolutionary development” as “there was no prior evidence of this alternative carcinogenesis.”
This oncologist, who was commissioned to discuss the study during the conference, stressed that it is an “important step for science”, hoping that it will also be “for society as well”, and considered that it “opens a wide door to knowledge but also to prevention.”
Prof Swanton said the next step would be to “understand why some of the altered lung cells turn into cancerous cells after exposure to pollutants”.
A number of researchers highlighted that this study confirms that reducing air pollution is also important for health.
Professor Swanton said: “We have a choice between smoking or not, but we can’t choose the air we breathe. It is therefore a global problem given that the number of people exposed to unhealthy levels of pollution is five times more likely than those exposed to tobacco smoke.”
More than 90 percent of the world’s population is exposed to what the World Health Organization describes as excessive levels of pollutants containing fine particulate matter.
This research also offers hope for new methods of prevention and treatment.
Suzette Delalog indicated the possibility of working on several methods of detection and prevention, but not in the short term, including “personal assessment of exposure to pollutants”, detection – not yet possible – of the EGFR genetic mutation, and other things.
As for Tony Mok of the University of Hong Kong, a statement of the European Society of Medical Oncology quoted him as saying that this research is “as interesting as it is promising,” and believed that it allows “one day to think about looking for precancerous lesions in the lungs using medical imaging techniques, and then try Treated with medications such as interleukin-1 beta inhibitors.”
Professor Swanton did not rule out finding “molecular cancer prevention with pills, perhaps one per day, to reduce the risk of cancer in high-risk areas”.
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