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Particle matter air pollution exposure may shorten HCC survival

Exposure to air pollution with particulate matter over 2.5 m in diameter, or PM2.5, after diagnosis of hepatocellular carcinoma had adverse effects in patients and may shorten overall survival, according to a retrospective study.

“The liver may be a target as PM2.5 can induce oxidative stress, inflammation, genotoxicity, and accelerate liver inflammation and steatosis, driving the development and progression of liver cancer,” the researchers wrote. “Our study provides ... evidence that exposure after HCC diagnosis to a major ambient air pollutant, PM2.5, is associated with shortened survival.”

The researchers collected data on patients newly diagnosed with primary HCC from the California Cancer Registry and data on PM2.5 air pollution from the U.S. Environmental Protection Agency’s Air Quality System database between 2000 and 2009. There were 20,221 patients who met the criteria of new HCC diagnosis and exposure to PM2.5.

At diagnosis, mean patient age was 63.7 years, 38.9% were white, 75% were men, 90.6% lived in metropolitan core areas and patients who lived in areas with high PM2.5 often had lower socioeconomic status. The stages of diagnosis included local (44.8%), regional (27.5%), distant (17.6%) or unknown (10%).

Patients diagnosed at local or regional stage who resided in areas with the lowest PM2.5 (less than 10 g/m³) had higher median all-cause mortality times compared with those in areas with the highest PM2.5 (30 g/m³ or more). In patients diagnosed at local stage, median survival was 2.16 years in the lowest PM2.5 bracket and 0.7 years in the PM2.5 highest bracket. Similarly, in those with regional diagnosis, the median survival was 0.61 years in the lowest bracket and 0.06 years in the highest bracket.

Among those from the highest exposure area, all-cause mortality rates were higher in patients diagnosed at local stage (HR = 10.24; 95% CI, 7.4-14.16), regional stage (HR = 4.6; 95% CI, 3.28-6.45), distant stage (HR = 2.6; 95% CI, 1.82-3.73) and overall (HR = 4.61; 95% CI, 3.87-5.5), compared with those from lower exposure areas.

“We found adverse effects of PM2.5 exposure after diagnosis on liver cancer survival,” the researchers concluded. “Not only were such effects more profoundly for those diagnosed with early stage, but they also increased strongly with concentration, suggesting that reductions in high PM2.5 exposure could increase survival for a nonrespiratory system cancer.” – by Talitha Bennett

Disclosure: The researchers report no relevant financial disclosures.