TUESDAY, Oct. 23 (HealthDay News) -- Using antiviral drugs to treat patients with chronic hepatitis C infection may greatly reduce their risk of liver cancer, according to a new study.

Hepatitis C is a leading cause of liver cancer and other liver diseases and is the leading cause of liver transplants. According to the U.S. Centers for Disease Control and Prevention, each year more than 15,000 Americans die from hepatitis C-related illness, such as cirrhosis and liver cancer. Deaths from the virus have been increasing for over a decade and are expected to increase in the coming years.

In the new study, Nina Kimer and colleagues at Copenhagen University in Denmark reviewed eight published clinical trials on the use of antiviral therapy -- interferon or pegylated interferon, or ribavirin, or a combination -- in patients with chronic hepatitis C infection.

Almost 1,200 patients in the studies received antiviral therapy. Most of them received interferon. The patients' antiviral treatment lasted between six months and a year and they were monitored for between five and eight years after treatment, along with another nearly 1,200 patients who did not receive antiviral treatment.

During follow-up, liver cancer was diagnosed in 81 patients who received antiviral treatment and in 129 patients who did not receive antiviral treatment. The Danish researchers concluded that antiviral therapy reduced the risk of liver cancer by 47 percent.

One expert not connected to the study said the results were encouraging.

"This study confirms something that most of us who treat hepatitis C knew on a gut level but had never seen demonstrated so effectively," said Dr. Douglas Dieterich, professor of liver diseases at Mount Sinai School of Medicine in New York City. Liver cancer "is the fastest growing cancer in the U.S., so this gives us great hope that by treating hepatitis C, we can now not only cure the virus but prevent [liver cancer] in the future," he said.

The findings are published Oct. 23 in the journal BMJ Open.

The researchers also reviewed five other studies of patients with chronic hepatitis C infection and said those findings showed that antiviral treatment reduced the risk of liver cancer by 70 percent.

The authors noted in a journal news release that standard treatment now consists of interferon plus ribavirin, which is considered more effective than either alone, and that the infection is usually identified earlier now than it used to be, before it causes extensive damage.

Another expert said that other treatment approaches might even exceed the results noted in this study.

"If we are able to extrapolate this data to the newer approved standard-of-care therapies, which have sustained viral response rates of greater than 70 percent, one would expect that these results would be even better in preventing the development of primary liver cancer," said Dr. David Bernstein, chief of the division of hepatology at North Shore University Hospital in Manhasset, N.Y. These improved outcomes "should encourage physicians to treat patient with advanced fibrosis and cirrhosis, and encourage those patients to seek out therapy," he added.

More information

The U.S. National Institute of Allergy and Infectious Diseases has more about hepatitis C.