Smoking is the major cause of lung cancer. But despite a decrease in smoking rates around the world, some countries have seen a baffling increase in rates of lung cancer, specifically in women who have never smoked. While the reasons behind this rise have remained relatively unknown, a new study by researchers from TFRI’s Pan-Can Lung Study has been able to pinpoint exactly why this is happening.
The culprit? Air pollution.
“Traditionally, exposure to second-hand smoke, workplace carcinogens, cooking and heating fumes, arsenic in drinking water or genetic susceptibility have been thought to be the reason why people who have never smoked develop lung cancer,” says Dr. Stephen Lam, a respirologist at BC Cancer and the study’s senior author. “Our study suggested exposure to ambient air pollutants, namely PM2.5, is probably the more important factor that needs to be focused on in future studies.”
The study, published in the Journal of Thoracic Oncology (June 2021), compared 1,005 cases of newly diagnosed lung cancer amongst never and ever smokers, focusing specifically on their sex, race, family history and exposure to outdoor and household air pollution exposure. What they found was enlightening: compared with ever smokers with lung cancer, never smokers with lung cancer were significantly younger, more frequently Asian, less likely to have chronic obstructive pulmonary disease or a family history of lung cancer, and had higher exposure to outdoor air pollution (PM2.5). This allowed them to conclude that air pollution is probably the most important factor in the development of lung cancer in people who have never smoked, especially among East Asian women.
This new information not only explains why more non-smokers are developing lung cancer, but also provides the basis for creating strategies to personalize screening programs for people with high-risk of developing cancer so they can be treated earlier, increasing their chances of survival.
“The ability to accurately assess lung cancer risk in people who have never smoked will provide them the opportunity to benefit from lung cancer screening using low-dose computed tomography,” says Dr. Lam.
High-Ambient Air Pollution Exposure Among Never Smokers Versus Ever Smokers With Lung Cancer
Renelle Myers, Michael Brauer, Trevor Dummer, Sukhinder Atkar-Khattra, John Yee, Barbara Melosky, Cheryl Ho, Anna L. McGuire, Sophie Sun, Kyle Grant, Alexander Lee, Martha Lee, Weiran Yuchi, Martin Tammemagi, Stephen Lam
The study was partially funded by the Terry Fox Translational Research Program grant to Early Detection of lung cancer