People with a certain type of hepatitis B (HBV), as well as a high viral load, face a higher risk of eventually developing liver cancer, according to a new study from Taiwan.1
It's estimated that about 1.25 million Americans are chronically infected with hepatitis B. Nearly a third of those acquired their infection in childhood. But there has been a dramatic reduction in the number of new infections among children and teens largely due to routine HBV vaccination. Symptoms of HBV include jaundice, fatigue, abdominal pain, no appetite, nausea and vomiting, and joint pain. The risk of death in those with chronic liver disease ranges from 15% to 25%.2
Effect of HBV Genotype and Viral Load
Doctors have long known that patients infected with chronic HBV face a higher risk of developing hepatocellular carcinoma, the most common form of liver cancer, especially when the viral infection progresses to cirrhosis.3 However, it's not clear whether the viral genotype infecting a particular person or the level of virus in their bloodstream plays a role in liver cancer risk, which was the focus of this research, says Ming-Whei Yu, PhD, at National Taiwan University in Taipei, the study's leader.
In HBV infection, there are seven genotypes, or strains, of the virus classified as genotypes A through G. Experts say while genotypes B and C are more prevalent in Asia, genotypes A and D are more common in the West.4
Yu's team conducted a retrospective study of more than 4,800 Taiwanese men diagnosed with hepatitis B infection between 1988 and 1992 who did not have hepatocellular carcinoma at that time. Blood samples were collected from each patient and the researchers conducted tests to determine HBV genotypes for 154 HBV patients who had subsequently been diagnosed with liver cancer during a 14-year follow-up period. Their risk of liver cancer was compared with a group of 316 people with HBV, but without cancer.
HBV Characteristics That Played a Role
In the end, Yu's group found that greater viral load was linked with an increased risk of liver cancer; men who had the highest viral levels in the study had more than 7 times the risk of liver cancer compared to those in the group with the lowest levels of the virus. In addition, genotype C was linked with 5 times the risk of developing liver cancer, the scientists discovered. This genotype was also associated with an increased viral load, suggesting a faster rate of viral replication in this group. Finally, men with both genotype C and a high level of virus in their blood faced the greatest odds of developing hepatocellular carcinoma: 26.5 times the risk compared to those with other genotypes and lower levels of HBV.
"[W]e found that higher plasma HBV DNA levels and infection with genotype C HBV were independently (and additively) associated with an increased risk of HCC among Taiwanese men," Yu and her colleagues wrote. "The longitudinal stability of these factors and their positive associations with hepatocellular carcinoma across 10-year age groups ranging from age 30 years to older than age 60 years suggest that they may be important markers for defining high-risk patients for antiviral treatment among HBV carriers."
'Strong Evidence' Noted
In an editorial accompanying the study, James Goedert, MD, of the Viral Epidemiology Branch of the National Cancer Institute wrote that this study carries "strong evidence that HBV genotypes matter" in defining which patients may face a higher risk of developing liver cancer. However, he added, "studies in other populations with different genotype distributions are needed to validate these associations and clarify whether they apply elsewhere."
1. Yu MW, Yeh SH, Chen PH et al. Hepatitis B virus genotype and DNA level in hepatocellular carcinoma: a prospective study in men. J Natl Cancer Inst 2005 Feb 16;97(4):265-72.
2. Centers for Disease Control and Prevention (CDC). Viral Hepatitis C. Available at: http://www.cdc.gov/ncidod/diseases/hepatitis/b/fact.htm. Accessed March 10, 2005.
3. Pons-Renedo F, Llovet JM. Hepatocellular carcinoma: a clinical update. Med Gen Med 2003 Jul 22;5(3):11.
4. Kao JH, Chen PJ, Lai MY, Chen DS. Genotypes and clinical phenotypes of hepatitis B virus in patients with chronic hepatitis B virus infection. J Clin Microbiol 2002 Apr;40(4):1207-9.
John Martin is a long-time health journalist and an editor for Priority Healthcare. His credits include coverage of health news for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
