He made the remarks in a keynote speech at the 12th Society of Chinese Bioscientists in America International Symposium held by Academia Sinica.

Lai, who is also president of National Cheng Kung University, said there are five types of hepatitis viruses -- A, B, C, D and E. The hepatitis viruses A and E can cause acute hepatitis, while the hepatitis B, C, and D viruses can cause chronic hepatitis.

Before a hepatitis B vaccine was developed, up to 90 percent of liver cancer was caused by hepatitis B. At present, as no vaccine is yet available against hepatitis C, half of the liver cancer cases in southern Taiwan are associated with hepatitis C, according to Lai.

There is an urgent need to develop hepatitis C vaccine as medications for hepatitis C treatment have been found ineffective for most patients and could cause side effects, Lai went on.

Patients with hepatitis B have 100 times higher risk of liver cancer than people who don't have hepatitis infection. Most people are infected with hepatitis C virus when they grow up and the duration of infection of the virus is normally shorter than that of people with hepatitis B virus, so under the circumstance, hepatitis C patients should have relatively low risk of liver cancer, Lai said.

However, if people who infected with hepatitis B and hepatitis C at the same time, hepatitis C patients have five times higher risk of liver cancer than hepatitis B patients, according to Lai.

The prevalence of hepatitis C virus infection in Taiwan is 2 percent, with the highest prevalence seen in a village in southern Taiwan, where 60 percent of the residents are infected with the virus, Lai noted.

Between 50 percent and 80 percent of those infected with hepatitis C have a tendency to develop chronic hepatitis, liver cirrhosis and carcinoma of the liver, Lai went on, adding that if hepatitis C patients drink alcohol or eat fatty food, their risk of developing liver cancer will be 10 times higher than that if they do not.

Lai suggested that hepatitis C patients refrain from drinking alcohol, eating fatty foods and taking uncertified medicines. He also advised them to undergo ultrasound examinations every four months for timely treatment.