The proportion of lung cancer cases among people who have never smoked is on the rise, with air pollution emerging as a key contributing factor, according to a new report by the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO).

The study, published in "The Lancet Respiratory Medicine", reveals that lung cancer in non-smokers is now the fifth leading cause of cancer-related deaths worldwide. Adenocarcinoma, the dominant subtype of lung cancer, is increasingly affecting never-smokers, with approximately 200,000 cases in 2022 linked to air pollution exposure. The highest burden of pollution-related adenocarcinoma was found in East Asia, particularly China.

Dr. Freddie Bray, head of IARC’s cancer surveillance branch and lead author of the study, emphasized the urgency of tracking evolving lung cancer risks and identifying environmental factors beyond smoking. "With declining smoking rates in countries like the UK and the US, the proportion of lung cancer cases among never-smokers is increasing," Bray told *The Guardian*. "Future strategies to combat lung cancer must address both tobacco use and air pollution."

Lung cancer remains the most common and deadly form of cancer worldwide, with 2.5 million new cases recorded in 2022. While smoking has long been the primary risk factor, shifting patterns indicate a growing impact of environmental pollutants. Adenocarcinoma now accounts for 45.6% of lung cancer cases in men and nearly 60% in women. Among non-smokers, it constitutes up to 70% of cases.

The study also highlights a significant shift in gender-related trends. While lung cancer incidence has generally declined among men over the past four decades, cases among women have continued to rise. In 2023, the UK recorded more women than men being diagnosed with lung cancer for the first time. Experts attribute this trend to historical smoking patterns but warn that increasing air pollution could further fuel the disease’s prevalence.

As researchers work to uncover other causes of lung cancer beyond smoking, the IARC urges global policymakers to strengthen tobacco control and air pollution reduction strategies. "Understanding the evolving risk factors for lung cancer is crucial for effective prevention efforts," Bray noted. "Reducing air pollution exposure is as important as combating tobacco use in the fight against lung cancer."

With lung cancer cases among never-smokers on the rise, experts stress the need for greater awareness and early detection. They encourage individuals to be vigilant about symptoms, just as they are with other cancers, such as breast cancer.