Impact of Pollution on Cancer: A Systematic Review and Meta-Analysis with Focus on Air Pollution

Pollution remains a major global public health concern increasingly associated with cancer incidence. This systematic review and meta-analyses examined the association between cancer risk and pollution across air, water, and land following the PRISMA guidelines. From 26,367 records initially identified in PubMed, Web of Science, and Scopus (January 2014-June 2025), 168 studies met the eligibility criteria. Meta-analyses conducted on 11 groups of studies revealed significant associations of lung cancer with fine particulate matter (HR_pooled = 1.347; 95% CI: 1.158-1.536), black carbon (HR_pooled = 1.096; 95% CI: 1.014-1.179) and ozone (HR_pooled = 0.941; 95% CI: 0.908-0.975), and breast cancer with nitrogen dioxide (HR_pooled = 1.064; 95% CI: 1.011-1.117). The association of ozone with cancer risks was inconsistent. While 155 studies reported on cancer risks from air pollution, only 10 studies focused on water pollutants and two on land pollutants, primarily heavy metals. Also, 79% of reviewed studies originated from only six high-income countries. The findings suggest that while particulate matter is a consistent risk factor, the global evidence base remains imbalanced based on pollution type and economic status of countries. Addressing these data gaps through targeted research in underrepresented regions and prioritizing the reduction of exposure to identified carcinogenic pollutants could reduce the global cancer burden.