Exposure to perfluoroalkyl substances and risk of hepatocellular carcinoma in a multiethnic cohort

Abstract

Background & aims: Exposure to poly- and perfluoroalkyl substances (PFAS), a class of persistent organic pollutants, is ubiquitous. Animal studies suggest that PFAS may increase risk of fatty liver and hepatocellular carcinoma (HCC) via impacts on hepatic lipid, amino acid, and glucose metabolism, but human data is lacking. We examined associations between PFAS exposure, altered metabolic pathways, and risk of non-viral HCC.

Methods: In this nested case-control study, pre-diagnostic plasma PFAS and metabolomics were measured in 50 incident HCC cases and 50 individually matched controls from the Multiethnic Cohort (MEC) study. Cases/controls were matched by age, sex, race, and study area. PFAS exposure and risk of HCC were examined using conditional logistic regression. A metabolome-wide association study and pathway enrichment analysis was performed for PFAS exposure and HCC risk, and key metabolites/metabolic pathways were identified using a meet in the middle approach.

Results: High perfluorooctane sulfonic acid (PFOS) levels (90^th percentile from NHANES; >55 μg/L) were associated with 4.5-fold increased risk of HCC (odds ratio 4.5, 95% CI 1.2-16.0). Pathway enrichment analysis showed that PFOS exposure was associated with alterations in amino acid and glycan biosynthesis pathways, which were also associated with HCC risk. We identified 4 metabolites linking PFOS exposure with HCC, including glucose, butyric acid (a short-chain fatty acid), α-ketoisovaleric acid (a branched-chain α-keto acid), and 7α-hydroxy-3-oxo-4-cholestenoate (a bile acid), each of which was positively associated with PFOS exposure and risk of HCC.

Conclusion: This proof-of-concept analysis shows that exposure to high PFOS levels was associated with increased risk of non-viral HCC, likely via alterations in glucose, amino acid, and bile acid metabolism. Larger studies are needed to confirm these findings.

Lay summary: Per- and polyfluoroalkyl substances (PFAS), often referred to as "forever chemicals" because they are difficult to break down and stay in the human body for years, are extremely common and can cause liver damage. In a first of its kind study, we found that exposure to high levels of perfluorooctanesulfonic acid, one of the most common PFAS chemicals, was linked to increased risk of hepatocellular carcinoma in humans. Hepatocellular carcinoma is difficult to treat and is one of the most common forms of liver cancer, and these findings may provide new avenues for helping to prevent this disease.

Keywords: Chemical exposure; HCC, hepatocellular carcinoma; HILIC, hydrophilic interaction chromatography; HRMS, high-resolution mass spectrometry; LC, liquid chromatography; MEC, Multiethnic Cohort; MWAS, metabolome-wide association; NAFLD, non-alcoholic fatty liver disease; PFAS, perfluoroalkyl substances; PFDA, perfluorodecanoate; PFHxS, perfluorohexane sulfonate; PFNA, perfluorononanoate; PFOA, perfluorooctanoate; PFOS, perfluorooctane sulfonate; PFUnDA, perfluoroundecanoic acid; RP, reverse phase; SEER, Surveillance, Epidemiology, and End Results; bile acid; exposome; hepatocellular carcinoma; metabolic pathway; metabolome; perfluorinated alkyl substance.

Graphical abstract

Fig. 1

Metabolic pathways associated with exposure to high levels of PFOS (on left) or HCC (on right) in 50 cases and 50 controls from the MEC cohort. Metabolic pathways are grouped into super pathways as indicated on the right of the plot. Metabolic pathway enrichment was performed using MetaboAnalyst version 5.0. Point size is proportional to the number of significant metabolites associated with each pathway. HCC, hepatocellular carcinoma; MEC, multiethnic cohort; PFOS, perfluorooctane sulfonic acid.

Fig. 2

Effect estimates for metabolites associated with high levels of PFOS and risk of HCC in 50 HCC cases and 50 controls from the MEC. For PFOS exposure, effect estimates were calculated using linear regression adjusting for age, sex, race/ethnicity, and study site, and indicate the mean difference and 95% CI in the log₂-transformed metabolite intensity between high (≥85^th percentile) vs. low levels of PFOS exposure. Effect estimates for HCC were calculated using conditional logistic regression, and indicate the OR and 95% CI for the risk of HCC per doubling of pre-diagnostic metabolite levels. HCC, hepatocellular carcinoma; MEC, multiethnic cohort; OR, odds ratio; PFOS, perfluorooctane sulfonic acid.