MELBOURNE, Australia – Up to 20 per cent of people diagnosed with lung cancer worldwide have never smoked, according to a major new review involving Australian and British researchers.
The study, published in the Journal of the American Medical Association (JAMA), analysed 92 international studies and found that between 15 and 20 per cent of lung cancer cases occur in people who have smoked fewer than 100 cigarettes in their lifetime.
Researchers from Australia’s Peter MacCallum Cancer Centre and the University of Melbourne, along with British colleagues, said the findings underscore that lung cancer is not exclusively a smoker’s disease.
Lead researcher Dr Benjamin J. Solomon said the review showed that non-smokers with lung cancer often carry unique genetic mutations linked to cancer development.
These differences, he added, could influence how well certain treatments work for them.
Most lung cancers in non-smokers were found to be adenocarcinomas—a type of cancer that begins in glandular cells lining the lungs.
The team identified several major risk factors for lung cancer among non-smokers, including exposure to second-hand smoke, air pollution, radioactive materials such as radon, and asbestos.
Having a close family member with lung cancer also appeared to increase risk.
Globally, lung cancer remains the leading cause of cancer deaths, responsible for about 1.8 million fatalities each year.
While smoking remains the main driver, experts say the rising incidence of lung cancer in people who have never smoked calls for greater awareness, early screening, and investigation into environmental and genetic causes.
