HEPATITIS-B VACCINATION AND REDUCED RISK OF PRIMARY LIVER-CANCER AMONG MALE-ADULTS - A COHORT STUDY IN KOREA

Background Primary liver cancer is an important health problem in Kore a, where hepatitis B virus (HBV) infection is prevalent. The authors c onducted a prospective cohort study to evaluate the protective effect of HBV vaccination against liver cancer in adults. Methods A total of 370 285 males aged greater than or equal to 30 comprised the study pop ulation. They were clinically free of liver diseases, and had not been vaccinated against HBV at enrolment. The results of HBV surface antig en (HBsAg) and antibody to HBsAg (antiHBs) marker positivity and those of the vaccination programme which took place during 1985 were used f or the construction of the cohort. About 5% (n = 18 914) were HBsAg po sitive, 78 094 were anti-HBs positive, and 273 277 were negative for b oth. Among the candidates for HBV vaccination (n = 273 277), 35 934 (1 3.2%) people had been vaccinated against HBV during 1985. Cases of liv er cancer were ascertained by record linkage and from medical records covering 1986-1989. A multivariate log-linear model was used to rest s tatistical significance and to estimate relative risks (RR). Results T he total follow-up period was 1 404 566 person-years, with an average of 3 years and 10 months. A total of 302 incident cases were ascertain ed. The overall incidence rate of liver cancer was 21.7 per 100 000 pe rson-years. With reference to the incidence level among the unvaccinat ed and uninfected the RR of primary liver cancer among the chronically infected and that of the unvaccinated and infected was 18.1 (95% CI: 14.2-22.9) and 0.34 (95% CI : 0.19-0.60), respectively. The RR among t he vaccinated group was 0.58 (95% CI : 0.31-1.09). Conclusions This st udy suggested that artificial immunization through HBV vaccination, ev en in adulthood, reduces the risk of liver cancer. It might also offer a practicable means of primary prevention, especially in areas with h yperendemicity of HBV infection.