Trends and territorial inequalities of incidence and survival of childhood leukaemia and their relations to socioeconomic status in Hungary, 1971-2015

Abstract

The Hungarian Childhood Cancer Registry, a population-based national registry of the Hungarian Paediatric Haemato-Oncology Network founded in 1971, monitors the incidence and mortality of childhood cancer. Our aims were to carry out a longitudinal study to investigate the trends and spatial inequalities of incidence and survival of leukaemia, and the association between survival and deprivation in Hungary. All cases of childhood leukaemia and myelodysplasia were analysed (3157 cases, 1971-2015, age: 0-14 years). Time trends and the annual percentage change in direct standardized incidence and mortality were assessed. Survival and association with deprivation were assessed using the Kaplan-Meier method and Cox regression. Incidence rates of leukaemia (23.5-56.0/million) increased with an average annual percent change (AAPC) of 1%, determined by an increase in the incidence of acute lymphoblastic leukaemia (14.6-39.2/million, AAPC: 1.25%). Kaplan-Meier analysis showed a significant improvement in overall survival over the study period. Starting from 25% of cases surviving 5 years in the 70s; the overall 5-year survival reached 80% by 2010. Survival differences were observed with sex, leukaemia type and age at diagnosis. A reverse association was found in the survival probability of leukaemia by degree of deprivation. The Cox proportional hazards model verified a significant reverse association with deprivation [hazard ratio=1.08 (1.04-1.12)]. This is the first nationwide study to confirm the prognostic role of deprivation on the basis of a large cohort of patients with childhood leukaemia during a 45-year period. To maintain further improvement in treatment results, it is important to detect inequalities. Our results showed that deprivation may also be important in the survival of leukaemia.