Lung cancer without smoking; study confirms pollution

MADRID (EFE).— One in four cases of lung cancer occurs in people who have never smoked, and until now, the cause was unknown.

A new international study published in the journal Nature has demonstrated, for the first time, that air pollution is not only associated with lung cancer in non-smokers, but can also directly cause it through genetic mutations.

The research was led by Ludmil Alexandrov of the University of California, San Diego, and Maria Teresa Landi of the National Cancer Institute in the United States.

Spanish scientists Pilar Gallego and Marcos Díaz-Gay from the Spanish National Cancer Research Centre (CNIO) also participated. The team analyzed lung tumors from 871 people who had never smoked, living in 28 regions across Africa, Asia, Europe, and North America, with varying levels of pollution.

By sequencing the entire genomes, they identified "mutational signatures," patterns of genetic damage that reveal past environmental exposures. The results show that those who lived in areas with greater pollution accumulated significantly more mutations: up to 3.9 times more mutations linked to smoking, and 76% more mutations related to cellular aging.

Furthermore, their telomeres—the protective ends of chromosomes—were shorter, a sign of accelerated biological aging.

“The more mutations there are, the more likely it is that one of them is responsible for the development of cancer,” explained Marcos Díaz-Gay, first author of the study.

Although not all mutations lead to disease, the study supports the hypothesis that environmental pollution acts as a key genomic trigger.

Furthermore, the study identified another worrisome environmental factor: aristolochic acid, present in some traditional medicinal herbs, which left a clear genetic trace in patients in Taiwan.

Although this acid has previously been linked to other types of cancer, this is the first time it has been associated with lung cancer.

On the other hand, researchers detected a completely new mutational signature, still without a known cause, that appears in 75% of tumors in nonsmokers, compared to 27% in smokers.

"We don't yet know what causes it, but it's the one that generates the most mutations in people who have never smoked," Díaz-Gay said.

The authors plan to expand the study to previously unexplored regions, such as Latin America, the Middle East, and parts of Africa, as well as evaluate new potential environmental risks, such as marijuana use, e-cigarette use, and exposure to radon gas.

Research Features

Pollution damages a person's DNA, hence the link between air and cancer.

In other areas

Researchers plan to expand their studies to previously unexplored regions, such as Latin America, the Middle East, and parts of Africa, as well as evaluate new potential environmental risks, such as marijuana use, e-cigarette use, and exposure to radon gas.