Smoking is not the only major factor in lung cancer

Smoking is not the only major factor in lung cancer

Some air pollutants appear to be a “hidden killer”, as they can cause a number of lung cancers in people who do not smoke, through a mechanism explained by a study published on Saturday, 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.

stealth killer

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.

While Professor Swanton reminded that the harm of air pollution has been known for a long time, he noted that scientists were "not sure whether or how this pollution directly causes lung cancer."

The researchers first studied data on more than 460 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.

250 samples

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.

"mystery"

Prof Swanton said that "these mutations may not be sufficient in themselves to lead to cancer, but when the cell is exposed to contamination, it is likely to stimulate some kind of reaction" inflammatory. 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 agents, 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 previous 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 be so “for society as well”, and considered that it “opens a wide door for knowledge but also for prevention.”

Reducing air pollution

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.

"We have a choice between smoking or not, but we can't choose the air we breathe," Swanton said. It is therefore a global problem given that the number of people exposed to unhealthy levels of pollution is likely to be five times greater 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.