Why is lung cancer increasing among women who never smoke?

Lung cancer cases are increasing in people who have never smoked, especially in women, a new study by the World Health Organization’s cancer agency has found.

The findings, published in The Lancet Respiratory Medicine, reveal that lung adenocarcinoma, the most common type of lung cancer among non-smokers, accounts for nearly 60% of lung cancer cases in women compared to 45% in men.

About 2.5 million new lung cancer cases were diagnosed worldwide in 2022 – an increase of 300,000 since 2020. The study suggests that environmental factors, particularly air pollution, along with genetic predisposition and immune responses, may be driving this rise in non-smoking-related lung cancer.

One of the most significant risk factors for lung cancer in non-smokers is genetic mutations, especially mutations in the EGFR gene. This gene provides instructions for producing a protein on the surface of cells involved in growth and division.

Mutations in this gene drive uncontrolled cell division and tumour growth. They are found in 50% of lung adenocarcinomas in non-smoking Asian women and 19% in non-smoking western women – compared with 10%-20% in non-smoking men.

Advances in genetic testing have made it easier to detect these mutations. However, rising exposure to air pollution, which is known to trigger EGFR mutations – may also be contributing to their increasing prevalence.

Other genetic changes that drive tumour...

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