Global impact of air pollution on cancer: causal evidence and health inequities across regions from 1990 to 2021.

BACKGROUND: This study explored the correlation and causation between air pollutants and cancer at both the macro level, using Global Burden of Disease (GBD) data, and the genetic level, based on Genome-Wide Association Study (GWAS) data. METHOD: This study investigated the impact of air pollution on cancer burden at global, regional, and national levels, analyzing variations across age groups and genders and exploring its association with the socio-demographic index (SDI). An ARIMA model was applied to predict the future prevalence of air pollution-related cancers through 2050. Additionally, the study examined the causal relationship between specific air pollutants and 17 types of cancer by conducting two-sample MR analyses, utilizing GWAS data from the UK Biobank and FinnGen databases to assess genetic susceptibility. RESULT: In 2021, air pollution contributed to approximately 0.37 million cancer-related deaths and 8.93 million DALYs, reflecting a declining trend in this0 health burden before 2020, followed by a slight increase in 2021. The highest burden was observed among individuals aged 75-90, with males being more affected. Projections indicate a likely decline in disease prevalence in high-SDI regions, while countries such as China and parts of Africa may face greater challenges by 2030 and 2050. Mendelian randomization analyses identified significant associations of PM₂.₅, NO₂, and NOx with bronchial and lung cancers and of NO₂ with stomach cancer, validated in both discovery and replication datasets, with the NO₂ association with gastric cancer remaining significant after adjustment for smoking. CONCLUSION: The GBD study revealed the macro-level impact of air pollution on cancer, with MR analysis confirming its genetic link. These findings underscore the urgent need for targeted policies and interventions to control air pollution and reduce the cancer burden.