Incidence of hepatocellular carcinoma in children in Khon Kaen before and after national hepatitis B vaccine program.

BACKGROUND

Hepatitis B virus infection is one of the most important risk factors for hepatocellular carcinoma. Hepatitis B vaccination has been obligatory in the Expanded Program on Immunization (EPI) in Khon Kaen since 1990.

OBJECTIVE

To compare the incidence of hepatocellular carcinoma in children in Khon Kaen province before and after the introduction of national hepatitis B vaccination program.

METHODS

Cases of liver tumors in children under 18, diagnosed during 1985-2007, were retrieved from the population-based cancer registry of Khon Kaen. Patients were divided into 2 groups, vaccinated and non-vaccinated with hepatitis B vaccine regarding the year of birth before or after 1990. Patients with diagnosis of liver cancer from any basis of diagnosis in population-based registration, except hepatoblastoma, were included. Patients without verified histology were assumed as having hepatocellular carcinoma if the age at diagnosis was over 10. Age-standardized incidence rates (ASRs) were analyzed and expressed as numbers per 1,000,000 population.

RESULTS

Fifteen patients aged 13 to 18 years were included in this study. The mean and median ages at diagnosis were 15.7 and 15 years respectively. Four children had a verified histology (age 14 to 18 years, median and mean = 16). The remaining 11 patients were diagnosed based on history and physical examination, radiology and death certificate, at the aged of 13 to 18 years. The ASRs for liver cancer in children over 10 years of age of non-vaccinated and vaccinated children were 0.88 and 0.07 per million respectively (p = 0.039). When calculated by including children at or older the 5 years of age, the ASRs for non-vaccinated and vaccinated cases were 0.97 and 0.24 per million respectively (p = 0.007).

CONCLUSIONS

The incidence of hepatocellular carcinoma is significantly lower in Thai children who receive hepatitis B vaccine at birth.