Hepatitis B vaccination and hepatocellular carcinoma rates in boys and girls

Context: Hepatocellular carcinoma (HCC) has a male predominance and is closely related to hepatitis B virus (HBV) infection. Hepatitis B virus vaccination was launched in 1984 in Taiwan for neonates of mothers carrying hepatitis B e antigen, resulting in a decreased incidence of HCC in children. The effect on boys vs girls is not known. Objective: To evaluate the association between a HBV vaccination program with incidence of childhood HCC by sex. Design and Setting: Analysis of data collected from Taiwan's National Cancer Registry System and the Taiwan Childhood Hepatoma Study Group between 1981 and 1996. Participants: Children aged 6 to 14 years who were diagnosed as having HCC (201 boys and 70 girls). Main Outcome Measure: Incidence of HCC in boys and girls before and after implementation of the vaccination program. Results: The boy-girl incidence ratio decreased steadily from 4.5 in 1981-1984 (before the program's introduction) to 1.9 in 1990-1996 (6-12 years after the vaccination program was launched). The incidence of HCC in boys born after 1984 was significantly reduced in comparison with those born before 1978 (relative risk [RR], 0.72; P=.002). No significant decrease in HCC incidence was observed in girls born in the same periods (RR, 0.77; P=.20). The incidence of HCC in boys remained stable with increasing age, while an increase of HCC incidence with age in girls was observed. These age and sex effects remained the same regardless of birth before or after the vaccination program. Conclusion: Our results suggest that boys may benefit more from HBV vaccination than girls in the prevention of HCC.