We combined information published worldwide on the seroprevalence of hepatitis B surface antigen (HbsAg) and antibodies against hepatitis C virus (anti-HCV) in 27 881 hepatocellular carcinomas (HCCs) from 90 studies. A predominance of HBsAg was found in HCCs from most Asian, African and Latin American countries, but anti-HCV predominated in Japan, Pakistan, Mongolia and Egypt. Anti-HCV was found more often than HBsAg in Europe and the United States. (Parkin et al, 2005). Relatively high incidence rates are also found in South Eastern Asia and in subSaharan Africa (Parkin et al, 2005). One of the least curable malignancies, HCC is the third most frequent cause of cancer death among men worldwide (Parkin et al, 2005).Chronic infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) are the most important causes of HCC (IARC, 1994). According to the World Health Organisation (WHO), approximately 350 million people are chronically infected with HBV (WHO, 2004) and 170 million with HCV (WHO and the Viral Hepatitis Prevention Board, 1999) worldwide. There are no comparable statistics for the number of individuals coinfected with both HBV and HCV.The relative importance of HBV and HCV infections in HCC aetiology is known to vary greatly from one part of the world to another (Parkin, 2006), and can change over time (Lu et al, 2006). In order to investigate this issue, we collated all published data on the prevalence of chronic HBV and HCV infection among HCC cases.
MATERIALS AND METHODSMEDLINE and WHO regional indexed databases were used to search for articles published from 1 January 1989 (after HCV testing became available) to 31 October 2006, by means of the MeSH terms: 'hepatocellular carcinoma', 'hepatitis B virus' and 'hepatitis C virus or hepacvirus'. Additional relevant studies were identified in the reference lists of selected articles. No language limitation was imposed. Eligible studies had to report prevalence of both hepatitis B surface antigen (HBsAg) and antibodies against HCV (anti-HCV), alone and in combination, for at least 20 HCC cases. To avoid multiple inclusions of the same HCC cases in more than one article, the time and place of recruitment of cases were cross-checked and the most recent publication was used. In the event that study methods indicated the availability of HBsAg and anti-HCV prevalence data but did not report both of them and the percent of coinfection in the article, authors were contacted for the supplementary information. In the course of contacting authors, additional data became available from one study expanded since the original publication (Appendix A).The key information extracted from each study were study country, gender distribution, generation of HCV serology tests used, prevalence of HBsAg alone (HBsAg þ ) and anti-HCV alone (anti-HCV þ ) and in combination (HBV/HCV coinfection), and the number of cases that were seronegative for both viral markers.Key information on 110 selected studies is given in the Appendix A by continent and country. For multicentric s...