An international team of scientists, led by Nanyang Technological University Singapore (NTU Singapore), has linked increase air pollution to an uptick in cases of lung adenocarcinoma (LADC) worldwide. The same study also concluded an overall lower consumption of tobacco worldwide is statistically linked to less people contracting lung squamous cell carcinoma (LSCC).
Lung adenocarcinoma is a type of cancer for which research strongly suggests that genetic, environmental, and lifestyle factors play a part, while lung squamous cell carcinoma is often linked to a history of smoking.
This study, done in collaboration between NTU and the Chinese University of Hong Kong, showed that a 0.1 micrograms per cubic metre (μg/m3) increment of black carbon, also known as soot, in the Earth’s atmosphere, is associated with a 12 per cent increase in LADC incidence globally.
Black carbon is a pollutant that is classified as under PM2.5, and the research team found that it has increased globally by 3.6 μg/m3 yearly from 1990 to 2012.
Meanwhile, a one per cent decline of smoking prevalence was associated with a nine per cent drop in LSCC incidence globally. The number of smokers worldwide decreased by 0.26 per cent a year, cumulatively falling by nearly six per cent from 1990 to 2012.
Lung cancer remains the leading cause of cancer with an estimated 1.8 million deaths in 2020, according to CA: A Cancer Journal for Clinicians. Global statistics have highlighted the trends of lung cancers, but understanding what may be causing them has been unclear, until the NTU-led study, which has associated the incidence of the cancers to tobacco consumption and air pollution.
Professor Joseph Sung, NTU’s Senior Vice President (Health and Life Sciences) and Dean, Lee Kong Chian School of Medicine (LKCMedicine), who led the study, said: “In our study, we were able to determine that the global increase of lung adenocarcinoma is likely associated with air pollution. It had always been unclear, in the past decades, why we are seeing more females and more non-smokers developing lung cancer worldwide. Our study points to the importance of environmental factors in the causation of specific types of lung cancer.”
From left to right: Assoc Prof Steve Yim and Prof Joseph Sung
Associate Professor Steve Yim, from NTU’s Asian School of the Environment, who holds an appointment at LKCMedicine, the first author of the study, said: “Our study provided us with an indication as to the reason behind the rising trend of lung adenocarcinoma, despite the decreasing trend of smoking prevalence. Our findings pinpoint the necessity and urgency to reduce air pollutant emissions especially black carbon.”
ASE Assoc Prof Steve Yim
The study analysed data from the World Health Organisation from 1990 to 2012 for data on lung cancers, while the dataset for age-standardised smoking prevalence rates from 1980 to 2012 was derived from the Institute for Health Metrics and Evaluation, an independent global health research centre at the University of Washington. The statistics on pollution were obtained from National Aeronautics and Space Administration (NASA). Pollutants that were analysed were black carbon, sulfate, and PM2.5.
The results of the study were published in the peer-reviewed academic journal Atmospheric Environment in November 2021. Read here for more details.