Viral hepatitis and liver cancer in Korea: an epidemiological perspective

In the past, hepatitis B virus (HBV) infection was endemic in the general Korean population. The association of HBV infection with the occurrence of liver cancer has been well demonstrated in several epidemiologic studies. While the mortality rates of liver cancer in Korea have decreased steadily over the last decade, the presence of hepatitis B surface antigen (HBsAg) in mothers remains high at 3-4%, and 25.5% of these HBsAg positive mothers are positive for hepatitis B e antigen (HBeAg). HBV infection caused almost a quarter of hepatocellular carcinoma (HCC) cases and one-third of deaths from HCC. These aspects of HBV infection prompted the Korean government to create a vaccination program against HBV in the early 1980s. In 1995, the Communicable Disease Prevention Act (CDPA) was reformed, and the government increased the number of HBV vaccines in the National Immunization Program (NIP), driving the vaccination rate up to 95%. In 2000, the National Health Insurance Act (NHIA) was enacted, which provided increased resources for the prevention of perinatal HBV infection. Then in 2002, the Korean government, in conjunction with the Korean Medical Association (KMA), launched an HBV perinatal transmission prevention program. The prevalence of HBsAg in children had been high (4-5%) in the early 1980s, but had dropped to below 1% in 1995, and finally reached 0.2% in 2006 after the NIP had been implemented. After the success of the NIP, Korea finally obtained its first certification of achievement from the Western Pacific Regional Office of the World Health Organization (WPRO-WHO) for reaching its goal for HBV control. An age-period-cohort analysis showed a significant reduction in the liver cancer mortality rate in children and adolescents after the NIP had been implemented. In addition to its vaccination efforts, Korea launched the National Cancer Screening Program (NCSP) for 5 leading sites of cancer, including the liver, in 1999. As a consequence of this program, the 5-year liver cancer survival rate increased from 13.2% (1996-2000) to 23.3% (2003-2008). The development of both the primary and secondary prevention for liver cancer including HBV immunization and cancer screening has been of critical importance.