Cancer breakthrough is a ‘wake-up’ call on danger of air pollution

Scientists have uncovered how air pollution causes lung cancer in groundbreaking research that promises to rewrite our understanding of the disease.

The findings outline how fine particulates contained in car fumes “awaken” dormant mutations in lung cells and tip them into a cancerous state. The work helps explain why so many non-smokers develop lung cancer and is a “wake-up call” about the damaging impact of pollution on human health.

“The risk of lung cancer from air pollution is lower than from smoking, but we have no control over what we all breathe,” said Prof Charles Swanton of the Francis Crick Institute, who presented the findings at the European Society for Medical Oncology conference in Paris on Saturday.

Smoking remains the biggest cause of lung cancer, but outdoor air pollution causes about one in 10 cases in the UK, and an estimated 6,000 people who have never smoked die of lung cancer every year. Globally, about 300,000 lung cancer deaths in 2019 were attributed to exposure to fine particulate matter, known as PM2.5, contained in air pollution.

However, the biological basis for how air pollution causes cancer has remained unclear. Unlike smoking or sun exposure, which directly causes DNA mutations linked to lung and skin cancer, air pollution does not cause cancer by triggering such genetic changes.

Instead, those with non-smoking lung cancer tend to carry mutations that are also seen in healthy lung tissue – small errors that we accumulate in our DNA throughout life and which normally remain innocuous.

“Clearly these patients are getting cancer without having mutations, so there’s got to be something else going on,” said Swanton, who is also Cancer Research UK’s chief clinician. “Air pollution is associated with lung cancer but people have largely ignored it because the mechanisms behind it were unclear.”

The latest work unveils this mechanism through a series of meticulous experiments showing that cells carrying dormant mutations can turn cancerous when exposed to PM2.5 particles. The pollutant is the equivalent of the ignition spark on a gas hob.