Hepatitis B virus (HBV) DNA is prone to mutations due to proofreading deficiencies of HBV polymerase. We have previously identified hepatocellular carcinoma (HCC) survival-associated HBV mutations in the X, precore, and core regions. In the present study, we extended our research to assess HCC survival-associated HBV mutations in the small S gene of HBV genome in 115 HCC patients including 60 patients with HBV B genotype, 52 patients with HBV C genotype, and 3 patients with other genotypes. The overfrequencies of mutations at nucleotides 529 and 735 are 8.5% and 91.5%, respectively, but the distribution frequencies of these mutations are not different between HBV genotypes B and C. Mutational sites 529 (relative risk: 3.611, 95% confidence interval [CI]: 1.414-9.221, P=0.007) and 735 (relative risk: 1.905, 95% CI: 1.101-3.297, P=0.021) were identified as statistically significant independent predictors for HCC survival by multivariate survival analysis using a Cox proportional hazards model. Moreover, the mutated 529A and 735T were associated with both short survival time and high HBV DNA load score in HCC patients. The analysis of DNA mutations in the HBV S gene may help identify HCC subgroups with poor prognosis and may provide reference for therapeutic decisions.
Keywords: HBV; HCC; S gene; mutations; survival.