Hepatitis B carriage explains the excess rate of hepatocellular carcinoma for Maori, Pacific Island and Asian people compared to Europeans in New Zealand

Background The aim of this research was to determine the hepatitis B surface antigen (HBsAg) carrier prevalence among cases of hepatocellular carcinoma (HCC), and the population attributable risk of HBsAg carriage for HCC, by ethnicity in New Zealand. Methods The hospital notes of HCC cases registered with the New Zealand Cancer Registry, for the years 1987-1994 inclusive, were viewed to determine the HBsAg status. Results The HBsAg status was determined for 193 cases of HCC. The HBsAg carrier prevalence for non-Europeans with HCC was markedly higher than that for Europeans, being 76.7% for Maori, 80.0% for Pacific Island people, and 88.5% for Asians, compared to 6.0% for Europeans. In addition to the effect of ethnicity, HCC cases aged <60 years were more likely to be HBsAg carriers than those aged greater than or equal to 60 years. The estimated population attributable risk of HBsAg for HCC, within each ethnic group, was only marginally less than the HBsAg prevalence due to the high relative risk of HBsAg carriage for HCC. The standardized incidence rate ratios of HCC for Maori, Pacific Island people and Asians compared to Europeans were 9.6, 20.4, and 22.3, respectively. Hepatocellular carcinoma attributable to HBsAg carriage explained 79%, 83%, and 92% of the excess standardized rate of HCC, compared to Europeans, for Maori, Pacific Island people, and Asians, respectively. Conclusions The HBsAg carrier prevalence in non-European cases of HCC in New Zealand is between 75% and 90%. HBsAg carriage explains the majority of the excess rate of HCC in non-Europeans compared to Europeans in New Zealand.