Infection with hepatitis B virus (HBV) causes liver cancer in some individuals, but not all strains of the virus are associated with the same degree of risk, according to a study published in the August 12 online issue of the Journal of the National Cancer Institute. If confirmed, the newly reported data could help target chemoprevention strategies in the future.
Researchers have previously identified eight genotypes of HBV and a variety of mutations in two regions of the viral genome, referred to as the precore and the basal core promoter. It was not known the extent to which different HBV genotypes or mutations are associated with the risk for liver cancer, which is also called hepatocellular carcinoma.
To find out, Chien-Jen Chen, Sc.D., of the Academia Sinica in Taipei, Taiwan, and colleagues characterized the viral DNA from 2,762 Taiwanese individuals who were infected with the virus but had not been diagnosed with liver cancer at the time of blood collection, which occurred during 1991 and 1992.
After a total follow-up of 33,847 person-years, 153 of these subjects have been diagnosed with liver cancer. HBV genotype C and a particular mutation in the basal core promoter (A1762T/G1764A) were associated with increased risk of liver cancer, while a mutation in the precore region (G1896A) was associated with a decrease in risk.
These data may help identify individuals "who are at an increased risk for liver disease progression and would therefore potentially benefit from early interventions, such as reg¬ular screening to detect disease progression, and treatment," the authors write.
In an accompanying editorial, Josep Llovet, M.D., of Mount Sinai School of Medicine in New York and Anna Lok, M.D., of the University of Michigan Medical Center in Ann Arbor review the previously known risk factors for liver cancer, prevention strategies to reduce the risk of HBV infection, and treatments for individuals who have already developed liver cancer.
"One of the main challenges is to determine whether secondary prevention can be accomplished with new antiviral therapies for HBV infection," the editorialists write. When secondary prevention strategies are tested in large randomized trials, patients should be stratified by known risk factors, including viral genotype and mutations.
- Yang et al. Associations Between Hepatitis B Virus Genotype and Mutants and the Risk of Hepatocellular Carcinoma. JNCI Journal of the National Cancer Institute, 2008; DOI: 10.1093/jnci/djn243
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