Ambient PM air pollution exposure and hepatocellular carcinoma incidence in the United States.

PURPOSE

To conduct the first epidemiologic study prospectively examining the association between particulate matter air pollution < 2.5 µm in diameter (PM) exposure and hepatocellular carcinoma (HCC) risk in the U.S.

METHODS

Surveillance, Epidemiology, and End Results (SEER) provided information on HCC cases diagnosed between 2000 and 2014 from 16 population-based cancer registries across the U.S. Ambient PM exposure was estimated by linking the SEER county with a spatial PM model using a geographic information system. Poisson regression with robust variance estimation was used to calculate incidence rate ratios and 95% confidence intervals (CIs) for the association between ambient PM exposure per 10 µg/m increase and HCC risk adjusting for individual-level age at diagnosis, sex, race, year of diagnosis, SEER registry, and county-level information on health conditions, lifestyle, demographic, socioeconomic, and environmental factors.

RESULTS

Higher levels of ambient PM exposure were associated with a statistically significant increased risk for HCC (n = 56,245 cases; adjusted IRR per 10 µg/m increase = 1.26, 95% CI 1.08, 1.47; p < 0.01).

CONCLUSIONS

If confirmed in studies with individual-level PM exposure and risk factor information, these results suggest that ambient PM exposure may be a risk factor for HCC in the U.S.