It's well known that people diagnosed with hepatitis C (HCV) face a higher risk of developing liver cancer.1 But now, a team of Japanese researchers has identified specific risk factors for the disease, known medically as hepatocellular carcinoma.2
What's the Risk in Hidden Hepatitis C?
Doctors in Osaka, Japan focused on the risk of liver cancer in people with asymptomatic hepatitis C. "The risk for hepatocellular carcinoma (HCC) among asymptomatic hepatitis C virus carriers is not well understood," they wrote.
To answer that lingering question, the investigators focused on nearly 2,000 people aged 40 years or older who had been diagnosed with hepatitis C and who had donated blood between 1991 and 1993. They were compared to a group of 150,000 people without the virus. All of the study participants were then followed for more than 8 years.
Some 2,500 individuals who were positive for hepatitis B surface antigen (HBsAg) (an indicator of HBV infection) and 25 people who had tested positive for both antibodies to HCV and HBsAg were included to determine the risk of cancer in those with the two indicators of hepatitis infection.
Risk Factors Uncovered
"The incidence of HCC among the HCV-positive individuals increased with age in both genders," wrote Hideo Tanaka, MD, who led the study, and his fellow researchers. Tanaka is a researcher in the department of Cancer Control and Statistics at Osaka Medical Center for Cancer and Cardiovascular Diseases.
"In the HCV-positive individuals, the cumulative risk of developing HCC between the ages of 40 and 74 years was 21.6% among males and 8.7% among females," the investigators wrote.
Tanaka's group also learned that hepatocellular carcinoma risk rose in a stepwise fashion as liver enzymes increased. These enzymes, such as alanine aminotransferase (ALT), are released into the bloodstream by the liver when it is damaged. Doctors use these higher enzyme levels as indicators of liver disease.3 By contrast, the risk of liver cancer increased as cholesterol levels incrementally dropped in these patients, the researchers reported.
"The 9-year cumulative incidence of HCC among individuals positive for HCV alone, those positive for HBsAg alone, and those positive for both was 3.0%, 1.0%, and 12.0%, respectively," they wrote.
Thus, the risk of liver cancer is increased in certain people with hepatitis C, Tanaka and his colleagues wrote, adding that "coinfection with HBV and HCV carried a superadditive risk" of liver cancer.
The Fifth Most Common Cancer
Hepatocellular carcinoma is the most common primary tumor of the liver in adults. It accounts for nearly 6% of all cancers, and is the fifth most common cancer in the world. In the United States and other Western countries, hepatitis C infection is a leading cause of liver cancer. Experts have found it usually develops in older people who have liver cirrhosis.4
It's estimated that 17,500 new cases of primary liver cancer and bile duct cancer will be diagnosed in the United States this year.5
1. Pons-Renedo F, Llovet JM. Hepatocellular carcinoma: a clinical update. Med Gen Med 2003 Jul 22;5(3):11.
2. Tanaka H, Tsukuma H, Yamano H, Ohima A, Shibata H. Prospective study on the risk of hepatocellular carcinoma among hepatitis C virus-positive blood donors focusing on demographic factors, alanine aminotransferase level at donation and interaction with hepatitis B virus. Int J Canc 2004 Dec 20;112(6):1075-80. Epub 2004 Aug 18.
3. Summaries for patients. New definitions for healthy ranges of alanine aminotransferase, a blood test of liver function. Ann Inern Med 2002 Jul 2;137(1):I37.
4. Pons-Renedo F, Llovet JM. Hepatocellular carcinoma: a clinical update. Med Gen Med 2003 Jul 22;5(3):11.
5. American Cancer Society. Overview: Liver Cancer: How Many People Get Liver Cancer? Available at: http://www.cancer.org/docroot/CRI/content
/CRI_2_2_1X_How_many_people_get_liver_cancer_25.asp?rnav=cri. Accessed January 5, 2005.
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.
