Heidi Ledford in Nature:
Air pollution could cause lung cancer not by mutating DNA, but by creating an inflamed environment that encourages proliferation of cells with existing cancer-driving mutations, according to a sweeping study of human health data and experiments in laboratory mice. The results, published in Nature on 5 April1, provide a mechanism that could apply to other cancers caused by environmental exposure — and might one day lead to ways to prevent them. “The idea is that exposures to carcinogens could promote cancer without actually doing anything to the DNA,” says Serena Nik-Zainal, a medical geneticist at the University of Cambridge, UK. “Not every carcinogen is a mutagen.”
Air pollution causes millions of deaths worldwide each year, including more than 250,000 from a type of lung cancer called adenocarcinoma. But it has been difficult to investigate how air pollution triggers cancer, in part because its effects are less pronounced than those of better-studied carcinogens such as tobacco smoke or ultraviolet light, says Nik-Zainal.