The good news. Scientists have discovered one way that air pollution can cause cancer, even in people who have never smoked.

How does air pollution cause lung cancer? The researchers found out that “normal” lung cells in some people who have never smoked have a rare mutation (EGFR mutation); however, most of these people do not get lung cancer.  The scientists also found that the chances of these cells becoming cancerous are higher in areas with a lot of air pollution. Finally, using mice, they discovered that the particles in air pollution (called PM2.5) can irritate these cells, causing them to grow and grow until a lung cancer is formed.

Why it’s significant.  Smoking is responsible for about 70% of lung cancers, leaving about 30% occurring in people who have never smoked. In fact, if lung cancer unrelated to smoking was classified as its own disease, it would be the 8th leading cause of cancer deaths. While it had widely been accepted that air pollution causes lung cancer, scientists never knew for certain how it did so. Now that we know, scientists may be able to identify ways to prevent PM2.5 from irritating lung cells which already have a EGFR mutation.

These findings were presented at the European Society for Medical Oncology (ESMO) Congress this month by Professor Charles Swanton. Cancer Research UK-funded scientists at the Francis Crick Institute and University College London (UCL) have revealed how air pollution can cause lung cancer in people who have never smoked. LCRF grantee, Mariam Jamal-Hanjani, MD, PhD, was a member of this team and her work an integral part of these findings.