Lung cancer cases among non-smokers are rising, with air pollution potentially contributing to the increase, according to a new study published in The Lancet Respiratory Medicine journal on World Cancer Day.
The findings of the study showed that adenocarcinoma, a cancer that originates in the glands that produce fluids such as mucus, accounted for 53-70 per cent of lung cancer cases in non-smokers globally in 2022.
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Unlike the other lung cancer types that they identified, adenocarcinoma is only weakly linked to cigarette smoking, the study notes. As smoking rates decline worldwide, the proportion of lung cancer cases among non-smokers has grown.
Adenocarcinoma has also become the most common type of cancer found across all sexes. In 2022, the study estimates there were 9.08 lakh new cases of lung cancer in women, with 59.7 percent being adenocarcinoma.
Additionally, 80,378 of these cases in women were linked to particulate matter (PM) pollution.
Experts from the International Agency for Research on Cancer (IARC) and the World Health Organization (WHO) led the study.
The teams analysed data from the Global Cancer Observatory, 2022, and other sources to categorise lung cancer cases into four subtypes: adenocarcinoma, squamous cell carcinoma, and small—and large-cell carcinoma.
As of 2019, nearly the entire global population lives in areas with air quality levels below WHO standards.
Lead author of the research study, Freddie Bray, head of IARC’s cancer surveillance branch, explained “The diverging trends by sex in recent generations offer insights to cancer prevention specialists and policy-makers seeking to develop and implement tobacco and air pollution control strategies tailored to high-risk populations.”
The authors also stated in the study that “lung cancer in people who have never smoked is estimated to be the fifth leading cause of cancer-related mortality worldwide, occurring almost exclusively as adenocarcinoma and most commonly in women and Asian populations.”