For people living with hepatitis B virus (HBV) or hepatitis C virus (HCV) infections-or both viruses together-the likelihood of developing liver cancer varies with gender and age, according to a study by researchers at Harvard University and published in the Journal of Clinical Oncology.

From 1991 to 1992, researchers enrolled a cohort a 23,820 Taiwan residents between the ages of 30 and 65. Samples for documenting HBV and HCV infections were collected at the start of the study.

During the follow-up period, 477 cases of liver cancer were documented.

People infected with both HBV and HCV had the highest risks of liver cancer. The lifetime risk, for those with blood samples indicating infection with both viruses, was more than 28 percent for men and over 27 percent for women. Among those with HBV infection, but not HCV infection, the risk was more than 27 percent for men and nearly 8 percent for women. And for those with evidence of HCV infection, but not HBV infection, the risks were more than 23 and 16 percent for men and women, respectively.

As for men and women without evidence of either HBV or HCV infection, the lifetime risk of liver cancer was slightly more than 1 percent.

The researchers found that among those who had only HCV and those who were co-infected with HBV and HCV, men were 1.4 times as likely as women to be diagnosed with liver cancer during their lifetimes. For those with HBV only, men were 3.4 times as likely as women to develop liver cancer.

Curiously, as the women living with HCV got older, their chances of developing liver cancer increased, while for the men with HBV, their chance of liver cancer decreased with age.