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Climate-sensitive exposures and cancer outcomes: a systematic review and meta-analysis
Alireza Negahi1, Amirhosein Naseri2, Hossein Najdsepas1
1Breast Health & Cancer Research Center, Iran University of Medical Sciences, Tehran, Iran.
International Journal of Biometeorology
|August 14, 2026
Summary
Climate change environmental exposures like wildfire smoke and air pollution have uncertain cancer risks. Research shows fragile, low-certainty evidence, highlighting the need for better studies on wildfire and PM2.5 carcinogenicity.
Area of Science:
- Environmental Health
- Oncology
- Climate Science
Background:
- Climate change exacerbates environmental exposures such as wildfire smoke, air pollution, extreme heat, and disasters.
- These exposures have plausible, yet unquantified, impacts on cancer incidence, mortality, survival, and recurrence.
- No prior synthesis has jointly examined these diverse exposures and cancer outcomes.
Purpose of the Study:
- To systematically synthesize evidence on the association between climate change-related environmental exposures and various cancer outcomes.
- To quantify the risks and assess the certainty of evidence for these associations.
Main Methods:
- Systematic literature search of five databases for observational studies up to May 2026.
- Inclusion of studies on wildfire, ambient temperature, disaster, precipitation anomaly, or PM2.5 exposure and cancer outcomes.
- Meta-analysis using random-effects models with robust variance estimation (RVE) to account for within-cohort dependence.
Main Results:
- The overall association between environmental exposures and cancer was null after accounting for within-cohort dependence (RVE 1.02 (0.93-1.11)).
- Uncorrected estimates were inflated due to correlated effects and high heterogeneity (I²=97%).
- Wildfire exposure showed a non-significant increase in cancer mortality; PM2.5 was linked to poorer survival; higher temperature effects were inconsistent.
Conclusions:
- The evidence is statistically fragile and of low certainty, not supporting a single overall effect.
- Priorities for future research include adequately powered, dependence-aware studies on wildfire and PM2.5 carcinogenicity within a planetary health framework.
- Disaster-related disruption of cancer care also requires further investigation.
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