In 2009, infection with the liver fluke Clonorchis sinensis (C. sinensis) was classified as "carcinogenic to humans" (Group 1) based on its involvement in the etiology of cholangiocarcinoma by the International Agency for Research on Cancer. However, little is known about the descriptive epidemiology of cholangiocarcinoma in Korea. We examined incidence trends of intrahepatic and extrahepatic cholangiocarcinomas, using data from the Korea National Cancer Incidence database for 1999-2005. The prevalence of C. sinensis infection was estimated from a recent population-based survey in rural endemic areas. Cholangiocarcinoma incidence rates are currently rising, even while primary liver cancer incidence rates are decreasing. Annual percent changes in cholangiocarcinoma incidence rates were 8% for males and 11% in females. Known areas of C. sinensis endemicity showed high incidence rates of cholangiocarcinoma. The positivity of C. sinensis eggs in stool samples from endemic areas was more than 25% of adults tested during 2005-2008. From a meta-analysis, the summary odds ratio for cholangiocarcinoma due to C. sinensis infection was 4.7 (95% confidence interval: 2.2-9.8). Approximately 10% of cholangiocarcinomas in Korea were caused by chronic C. sinensis infections. More specific policies, including health education and an extensive effort for early detection in endemic areas, are needed.
Adult ; Aged ; Aged, 80 and over ; Animals ; Bile Duct Neoplasms/*epidemiology/parasitology ; Bile Ducts, Intrahepatic/parasitology/*pathology ; Cholangiocarcinoma/*epidemiology/parasitology ; Clonorchiasis/*epidemiology ; Female ; Humans ; Korea/epidemiology ; Male ; Middle Aged

Liver fluke disease is a chronic parasitic inflammatory disease of the bile ducts. Infection occurs through ingestion of fluke-infested, fresh-water raw fish. The most well-known species that cause human infection are Clonorchis sinensis, Opisthorchis viverrini and Opisthorchis felineus. Adult flukes settle in the small intrahepatic bile ducts and then they live there for 20-30 years. The long-lived flukes cause long-lasting chronic inflammation of the bile ducts and this produces epithelial hyperplasia, periductal fibrosis and bile duct dilatation. The vast majority of patients are asymptomatic, but the patients with heavy infection suffer from lassitude and nonspecific abdominal complaints. The complications are stone formation, recurrent pyogenic cholangitis and cholangiocarcinoma. Approximately 35 million people are infected with liver flukes throughout the world and the exceptionally high incidence of cholangiocarcinoma in some endemic areas is closely related with a high prevalence of liver fluke infection. Considering the impact of this food-borne malady on public health and the severe possible clinical consequences, liver fluke infection should not be forgotten or neglected.
Animals ; Bile Duct Neoplasms/*diagnosis/epidemiology/*parasitology ; Bile Ducts, Intrahepatic/*parasitology ; Biological Markers/analysis ; Cholangiocarcinoma/*diagnosis/epidemiology/*parasitology ; Cholangitis/diagnosis/parasitology ; Clonorchiasis/*complications/*diagnosis/epidemiology/parasitology ; Clonorchis sinensis ; Humans ; Incidence ; Opisthorchiasis/*complications/*diagnosis/epidemiology/parasitology ; Opisthorchis