Hepatitis B virus markers in hepatitis B surface antigen negative patients with pancreatic cancer: Two case reports

BACKGROUND Hepatitis B virus (HBV) is a known carcinogen that may be involved in pancreatic cancer development. Detection of HBV biomarkers [especially expression of HBV regulatory X protein (HBx)] within the tumor tissue may provide direct support for this. However, there is still a lack of such reports, particularly in non-endemic regions for HBV infection. Here we present two cases of patients with pancreatic ductal adenocarcinoma, without a history of viral hepatitis, in whom the markers of HBV infection were detected in blood and in the resected pancreatic tissue. CASE SUMMARY The results of examination of two patients with pancreatic cancer, who gave informed consent for participation and publication, were the source for this study. Besides standards of care, special examination to reveal occult HBV infection was performed. This included blood tests for HBsAg, anti-HBc, anti-HBs, HBV DNA, and pancreatic tissue examinations with polymerase chain reaction for HBV DNA, pregenomic HBV RNA (pgRNA HBV), and covalently closed circular DNA HBV (cccDNA) and immunohistochemistry staining for HBxAg and Ki-67. Both subjects were operated on due to pancreatic ductal adenocarcinoma and serum HBsAg was not detected. However, in both of them anti-HBc antibodies were detected in blood, although HBV DNA was not found. Examination of the resected pancreatic tissue gave positive results for HBV DNA, expression of HBx, and active cellular proliferation by Ki-67 index in both cases. However, HBV pgRNA and cccDNA were detected only in case 1. CONCLUSION These cases may reflect potential involvement of HBV infection in the development of pancreatic cancer.