Global Rise in Lung Cancer Cases Among Non-Smokers Sparks Concern

The proportion of lung cancer diagnoses among people who have never smoked is rising, with air pollution identified as a significant contributing factor, according to the World Health Organization’s cancer agency.

Lung cancer in never-smokers is now estimated to be the fifth leading cause of cancer-related deaths worldwide, as reported by the International Agency for Research on Cancer (IARC).

This form of lung cancer is occurring predominantly as adenocarcinoma, which has emerged as the most common subtype among both men and women globally. The IARC study, published in The Lancet Respiratory Medicine journal, found that approximately 200,000 cases of adenocarcinoma in 2022 were linked to air pollution exposure.

The highest burden of pollution-related adenocarcinoma was observed in East Asia, particularly in China.

Dr. Freddie Bray, the lead author of the study and head of the IARC’s cancer surveillance branch, emphasized the urgent need to monitor the evolving risk factors of lung cancer. He stressed the importance of further research to identify additional causes, particularly in populations where smoking is not the primary driver of lung cancer cases.

“With declining smoking rates in countries like the UK and the US, the proportion of lung cancer cases among never-smokers is increasing,” Bray noted. “The future trend of adenocarcinoma attributable to air pollution will depend on the success of global efforts to reduce tobacco use and environmental pollution.”

Lung cancer remains the leading cause of cancer-related illness and death worldwide, with approximately 2.5 million new cases reported in 2022. However, the incidence patterns by subtype have changed significantly in recent decades.

Adenocarcinoma has become the most prevalent subtype, accounting for 45.6% of global lung cancer cases in men and 59.7% in women in 2022, compared to 39.0% and 57.1% respectively in 2020. Among never-smokers, adenocarcinoma represents up to 70% of lung cancer cases.

While lung cancer rates in men have generally declined over the past 40 years, cases among women continue to rise. In 2022, men accounted for approximately 1.6 million lung cancer cases, while around 900,000 cases were diagnosed in women. The narrowing gap between male and female lung cancer incidences underscores shifting risk factors. rise

Changes in cigarette manufacturing, smoking patterns, and environmental conditions have influenced these trends, with mounting evidence pointing to air pollution as a significant contributor to the rise in adenocarcinoma cases.

Although the exact proportion of lung cancer cases occurring in never-smokers remains unknown, evidence suggests it is increasing. Scientists are actively researching other potential causes beyond smoking.

“Air pollution is a key factor in the growing prevalence of adenocarcinoma, which now accounts for 53% to 70% of lung cancer cases among never-smokers worldwide,” the study concluded. rise

Bray emphasized that understanding these shifting trends in lung cancer and its risk factors is crucial for developing effective prevention strategies. “Changes in smoking behaviors and exposure to air pollution are among the main determinants influencing lung cancer risk today,” he said. “The differing trends by sex offer valuable insights for policymakers and cancer prevention specialists working to implement targeted tobacco control and air pollution reduction strategies.” rise