Background/aims: This study aimed to measure the intrahepatic total hepatitis B virus (HBV) DNA and covalently closed circular DNA (cccDNA) levels in tumor and non-tumor tissues in hepatocellular carcinoma (HCC) patients.
Methods: Intrahepatic total HBV DNA and cccDNA were measured in 25 HCC patients (21 hepatitis B surface antigen [HBsAg]-positive and 4 HBsAg-negative) by the Invader assay.
Results: A low level of intrahepatic HBV DNA was detectable in all HBsAg-negative patients. For HBsAg-positive patients, the intrahepatic total HBV DNA levels in the tumor and non-tumor tissues were comparable (P=0.903). However, the tumor tissues had significantly higher levels of cccDNA (0.35 vs. 0.16 copies/cell, P=0.030) and higher proportion of intrahepatic HBV DNA in the form of cccDNA (100% vs. 84%, P=0.004) than the non-tumor tissues. Seventeen out of 21 (81%) tumor tissues had intrahepatic HBV DNA solely in cccDNA form. Analysis of HBV mRNA expression indicated that HBV replication appeared to be lower in the tumor tissues than the non-tumor tissues.
Conclusions: Compared to the non-tumor tissues, the levels of HBV replication in the tumor tissues appeared to be lower, and cccDNA was the predominant form of HBV DNA in the tumor tissues.