Fine particles in exhaust gases and fumes from the combustion of fossil fuels can cause lung cancer in non-smokers. The fact is known and would be responsible for 250,000 lung cancer deaths worldwide each year. But we did not know how, or which population was more particularly susceptible.
In a study, presented Saturday, September 10 at the congress of the European Society for Medical Oncology (ESMO)which is held until Tuesday in Paris, researchers from the Francis Crick Institute in London (England) lift part of the veil. “The risk of lung cancer is certainly lower than that linked to smoking, but we do not control what we breathe, underlines the Pr Charles Swanton, lead author of the study. Our actions against climate change, which involve reducing pollution, are intimately linked to our health. »
Genetic mutation
The study, involving half a million people living in England, South Korea and Taiwan, shows that exposure to fine particles increases the risk of lung cancer in people with a mutation in a gene called EGFR. This mutation is found in nearly half of non-smokers with lung cancer. The researchers also studied cells carrying another mutant gene (KRAS), known to be linked to lung cancer, in the laboratory.
In the presence of atmospheric pollutants, some of these cells turn into cancer stem cells. At the same time, pollution stimulates the production of inflammatory substances, increasing the proliferation of mutated cells in contact with the particles and the risk that they will transform.
Genetic mutations alone would, however, only have a small impact on the appearance of cancer. “It is indeed exposure to pollutants that increases their carcinogenic potential, says Professor Swanton. You need a promoter to induce cancer. It is a model which had been theorized as early as 1947, but which has been neglected. Cigarette smoke is, of course, also a promoter. And you have to wonder about vaping. »
A question arises: will we be able, in the future, to easily identify the carriers of this mutation of the EGFR gene, which would appear most often with age, and prescribe control examinations for them?