Childhood leukaemia incidence in Hungary, 1973-2002. Interpolation model for analysing the possible effects of the Chernobyl accident.

The incidence of childhood leukaemia in Hungary has yet to be reported, although data are available since the early 70s. The Hungarian data therefore cover the time before and after the Chernobyl nuclear accident (1986). The aim of this study was to assess the effects of the Chernobyl accident on childhood leukaemia incidence in Hungary. A population-based study was carried out using data of the National Paediatric Cancer Registry of Hungary from 1973 to 2002. The total number of cases was 2204. To test the effect of the Chernobyl accident the authors applied a new approach called 'Hypothesized Impact Period Interpolation'-model, which takes into account the increasing trend of childhood leukaemia incidence and the hypothesized exposure and latency times. The incidence of leukaemia in the age group 0-14 varied between 33.2 and 39.4 per million person-years along the observed 30 year period, and the incidence of childhood leukaemia showed a moderate increase of 0.71% annually (p = 0.0105). In the period of the hypothesized impact of the Chernobyl accident the incidence rate was elevated by 2.5% (95% CI: -8.1%; +14.3%), but this change was not statistically significant (p = 0.663). The age standardised incidence, the age distribution, the gender ratio, and the magnitude of increasing trend of childhood leukaemia incidence in Hungary were similar to other European countries. Applying the presented interpolation method the authors did not find a statistically significant increase in the leukaemia incidence in the period of the hypothesized impact of the Chernobyl accident.