Media release

From: The Lancet

The Lancet Respiratory Medicine: The proportion of never-smokers diagnosed with lung cancer is on the rise, new global analysis suggests

A new study published in The Lancet Respiratory Medicine journal examines variations in lung cancer incidents worldwide. The study finds that of the four main subtypes of lung cancer (adenocarcinoma, squamous cell carcinoma, small-cell carcinoma, and large-cell carcinoma), adenocarcinoma has become the dominant subtype among both men and women. Adenocarcinoma accounted for 53%–70% of lung cancer cases among never-smokers worldwide suggesting that the risk of lung cancer linked to air pollution is on the rise, especially in eastern Asia and China.  

Lung cancer remains the leading cause of cancer-related morbidity worldwide with approximately 2.5 million people diagnosed with lung cancer globally in 2022. Current trends suggest that while men still make up most lung cancer cases (approximately 1.6 million new cases in 2022), the gap between lung cancer incidences in males and females is narrowing, with nearly 910,000 women diagnosed with lung cancer in 2022. Specifically, the rising trends of lung cancer incidence among females appear to be driven by increasing rates of adenocarcinoma. These shifts can be attributed to the changing patterns of cigarette smoking over the past several decades, including smoking prevalence, tobacco type, smoking habit, smoking intensity, and smoking initiation and cessation.

As smoking prevalence continues to decline in many countries worldwide, the proportion of lung cancer in never-smokers has increased. Lung cancer in never-smokers 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. Of those diagnosed with Adenocarcinoma, nearly 200,000 of the cases were associated with exposure to air pollution.  

The authors say the study’s findings underscore the need for continued monitoring of the changing risk of lung cancer, and for further studies that identify possible causal factors, such as air pollution, in populations where smoking is not considered the major cause of lung cancer.