ASPO Abstracts
Wildfire air pollution and cancer survival in the United States
Category: Molecular Epidemiology & Environment
Conference Year: 2023
Abstract Body:
Background: Climate change has led to an increase in the frequency, duration, and intensity of wildfires. Wildfire smoke, which includes particulate matter <2.5 microns in diameter (PM2.5), is an important source of outdoor air pollution. Although PM and outdoor air pollution are established risk factors for cancer, there is little research exploring the association between wildfires specifically and cancer survivorship. Study objective: To examine the associations between PM2.5 exposure and wildfire locations in relation to mortality among cancer patients. Methods: Surveillance, Epidemiology, and End Results (SEER) provided information on cancer cases diagnosed between 2000 and 2019 from population-based cancer registries across the United States. Average annual PM2.5 concentrations (from a spatiotemporal exposure model incorporating Environmental Protection Agency air monitoring data) and annual wildfire data (number of events and area burned) from the Monitoring Trends in Burn Severity were linked with SEER-provided year and county of residence at diagnosis using a geographic information system. Cox regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusting for individual-level age, sex, race/ethnicity, marital status, year, and SEER registry, and county-level information on socioeconomic status and health and lifestyle factors. Results: There was a positive association between PM2.5 exposure (adjusted HR per 10 µg/m3 increase: 1.05, 95% CI 1.03-1.07) and cardiopulmonary mortality (n=458,757) among cancer patients (total n=6,606,286), which was stronger in counties where a relatively larger percentage of the area (highest tertile: 0.60-50.43%) was burned by wildfires (adjusted HR: 1.10, 95% CI 1.01-1.20) (p interaction=0.04). There were generally positive associations with PM2.5 and all-cause (n=3,143,890), all-cancer (n=2,179,075), and other (n=506,058) mortality. Conclusions: We observed a stronger positive association for PM2.5 exposure on cardiopulmonary mortality among cancer patients residing in areas more heavily impacted by wildfires. Future research should confirm these findings using individual-level data and information on pollutants specifically emitted from wildfire smoke.
Keywords: wildfires; air pollution; cancer survivorship; geospatial science; environmental epidemiology