The first study to show how air pollution causes cancer in non-smokers

British researchers have found that air pollution awakens old and damaged cells that become cancerousThe discovery could mark a “new era” by allowing the development of drugs that stop the formation of these cancersThe idea of ​​taking a pill to block cancer if you live in a highly polluted area is not a pipe dream In recent years, various clinical studies have linked exposure to air pollution with an increased risk of cancer and lung disease. According to the World Health Organization, the global incidence of respiratory cancers continues to grow, with new annual cases expected to increase by around 70% over the next two decades. One of the most recent studies, published earlier this year in The journal The Lancet Planetary Health, indicated that air pollution in cities caused more than 1.8 million premature deaths worldwide in 2019. Now, a team led by Charles Swanton, an oncologist and researcher at the Francis Crick Institute (United Kingdom), has identified the exact mechanism through which air pollution triggers lung cancer in non-smokers. Guilty, the particles produced by the combustion of hydrocarbonsThe reason why many people who have never smoked get lung cancer is because of very small pollutant particles that are suspended in the air, PM2.5, which are less than 2.5 microns wide, much less than the diameter of a human hair. The conclusions have been presented by the Swanton team together with University College London at the ESMO 2022 congress taking place these days in Paris (France). These particles, which are usually found in vehicle exhaust pipes and in smoke from fossil fuels, are associated with the risk of non-small cell lung cancer (NSCLC) and it is suggested that they may be responsible for more than 250,000 lung cancer deaths per year worldwide. Scientists analyzed the health data of more than 460,000 people in England, South Korea and Taiwan. They found that exposure to these tiny pollution particles (PM2.5). led to an increased risk of mutations in the EGFR gene. In addition, in laboratory studies with mice, the team showed that the particles caused changes in the EGFR gene and the KRAS gene, both of which are linked to lung cancer. nearly 250 samples of human lung tissue never exposed to carcinogens from smoking or heavy pollution. Although the lungs were healthy, they found DNA mutations in 18% of the EGFR genes and 33% of the KRAS genes. The mutations are established in the cells and can lie dormant, but they can also eventually lead to cancer. Researchers have shown that the damage is already there, in our cell’s DNA, generated as we grow and age, but it takes something to pull the trigger for it to actually turn cancerous, and that’s PM2.5. that the study has shownThrough their experiments, both with humans and animals, they have been able to show that:In places with higher levels of air pollution, there are more lung cancers not caused by smoking.Breathing PM2.5 causes the release of an alarm chemical, interleukin-1-beta, in the lungs. This causes inflammation and activates cells in the lungs to help repair any damage. But about one in 600,000 cells in the lungs of a 50-year-old years old already contains potentially cancerous mutations. These cells are acquired as we age, but appear completely healthy until they are triggered by the chemical alarm and become cancerous. Scientists managed to stop the formation of cancers in mice exposed to air pollution by using a drug that blocks the alarm signal. A pill that blocks lung cancer? That mutations alone are not always enough to cause cancer and that an extra element is needed is, according to Swanton, the most exciting finding that his laboratory has found, since “it really reconsiders our understanding of how tumors start.” new era” of molecular cancer prevention. The idea of ​​taking a pill to block cancer if you live in a highly polluted area is not a pipe dream. Doctors have already tested the drug interleukin-1-beta in cardiovascular diseases and discovered, by accident, that it reduces the risk of lung cancer. Double advance The results represent a double advance, on the one hand they help to understand the impact of air pollution and on the other, they teach us how we develop lung cancer. Dr. Emilia Lim, one of the researchers on Crick’s team, said that people who have never smoked but have developed lung cancer wonder why. “Giving them some clues as to how this might work is very, very important,” she said. “99% of people in the world live in places where air pollution exceeds the WHO parameters, so it really affects us all.”Reducing pollutionSwanton called air pollution a “hidden killer”, noting that research estimates it is linked to the deaths of eight million people a year, about the same number as tobacco. “You and I can choose whether or not we smoke, but we can’t choose the air we breathe,” said the scientist at the helm of the research, who is also the clinical director of Cancer Research UK, the main funder of the research. “Given that probably five times more people are exposed to unhealthy levels of pollution than tobacco, you can see that this is a pretty big global problem,” he argued. “We can only address it if we recognize the really intimate links between climate health and human health.”