Epigenetic age acceleration of early stage hepatocellular carcinoma tightly associated with hepatitis B virus load, immunoactivation, and improved survival.

Properly stratifying high-risk individuals with early stage hepatocellular carcinoma (HCC) is essential to identify patients in which the potentially therapies can be offered. To this context, we systematically investigated the prognostic value of epigenetic clock with early stage HCC as well as the association with other molecular characteristics. We computed DNA methylation (DNAm) age of 256 early stage HCC patients and 50 normal samples from TCGA by Horvath clock model. The characteristics of two DNAm age subgroups were differentiated regarding HBV expression, pathway activity, epigenomic, and genomic alteration. Cox regression and restricted cubic spline (RCS) analysis were utilized to evaluate the prognostic value of epigenetic acceleration. DNAm age was significantly associated with chronological age in normal tissue but largely disrupted in tumors (P< .001), and showed significant negative correlation with HBV expression (P< .05). We identified two DNAm age groups (DNAmAge-ACC and DNAmAge-DEC), and the former presented with an immunoactive phenotype (all FDRs<0.05 in enrichment analysis), CpG island hypermethylation (P< .001), and lower mutation burden (P= .018). Every 10-year increase in DNAm age was associated with a 18% decrease in fatality after adjustment for major clinical variables; DNAmAge-ACC had 50% lower mortality risk than DNAmAge-DEC (HR: 0.50, 95% CI: 0.27-0.94, P= .03). RCS revealed the fatality risk significantly decreased as epigenetic age accelerated (P = .04). Conclusions. In summary, we highlighted the prognostic value of epigenetic age acceleration for early stage HCC; better prognosis, relatively lower HBV load, and higher enrichment of immune signatures were tightly associated with epigenetic age accelerated tumors.