Hepatitis B virus pre-S deletion mutations are a risk factor for hepatocellular carcinoma: a matched nested case-control study

A matched nested case-control study of 33 paired cases and controls was conducted, based on a study cohort in Long An county, Guangxi, China, to determine whether infection with hepatitis B virus (HBV) with pre-S deletions is independently associated with the development of hepatocellular carcinoma (HCC), without the confounding effects of basal core promoter (BCP) double mutations. The prevalence of pre-S deletions was significantly higher in HCC (45.5%, 15 of 33) than the controls (118.2%, 6 of 33) (P<0.01), under the control of the influence of BCP double mutations. Most of the pre-S deletions occurred in, or involved, the 5' half of the pre-S2 region and the difference between HCC (93.3%, 14 of 15) and controls (66.7%, four of six) was significant for this region (P=0.015). There was no significant difference in pre-S deletions between the BCP mutant group and BCP wild-type group (P>0.05), nor was the prevalence of pre-S deletions significantly different between genotypes B and C (P>0.1). These results suggest that pre-S deletions constitute an independent risk factor for HCC and their emergence and effect are independent of BCP mutations. The 5' terminus of pre-S2 is the favoured site for the deletion mutations, especially in HCC cases. Further prospective studies are required to confirm the role of these mutations in the development of HCC.