A potential association between exposure to hepatitis B virus and small bowel adenocarcinoma.

Chronic infection with hepatitis B virus (HBV) has never been described as a risk factor for small bowel adenocarcinoma, although infection is a known risk factor for hepatocellular carcinoma. From May 2009 to December 2014, we implemented an institution-wide screening program for hepatitis B viral serologies prior to starting chemotherapy. Evidence of exposure [hepatitis B core antibody (anti-HBc) positivity in the absence of hepatitis B surface antigen (HBsAg) positivity] was highest in patients with hepatocellular carcinoma (21.1%), followed by small bowel cancer (12.5%). The small bowel adenocarcinoma cases with anti-HBc positivity were reviewed. Special attention was paid to known risk factors for small bowel cancers. One patient had a diagnosis of hereditary nonpolyposis colorectal cancer (HNPCC). However, the other patients had no genetic syndromes, history of inflammatory bowel disease or other chronic inflammation to explain their risk. We postulate exposure to bile acids, tumorigenesis of hepatocytes and cholangiocytes, and/or damage to the intestinal mucosa secondary to HBV exposure/infection as potential mechanisms for development of small bowel adenocarcinoma. More research is warranted to further elucidate this association.