Trends in paediatric central nervous system tumour incidence by global region from 1988 to 2012

Background: Central nervous system (CNS) tumours comprise 20% of childhood cancers worldwide. Whether childhood CNS tumour incidence has increased over time across geographic regions remains to be explored. Methods: We identified CNS cancers in the Cancer in Five Continents (CI5) data and estimated age standardized incidence rates (ASRs; cases/million children) and 95% confidence intervals (95% CI), male-to-female incidence rate ratios (IRR; 95% CI) and average annual percent change in incidence (AAPC; 95% CI) by geographic region for children aged 0-19 years where data were available using Poisson regression and generalized estimating equations (GEE). Cancers included: astrocytic tumours, medulloblastoma, ependymal, oligodendroglial and mixed glioma, glioma of uncertain origin, and other embryonal tumours. Geographic regions were defined using the United Nations geoscheme. Results: There were 56 468 CNS cancers included in the study. ASRs were highest for astrocytic tumours globally in 2012 (ASR: 5.83; 95% CI: 5.68-5.99). Globally, all cancers exhibited a male excess in incidence. Regionally, only medulloblastoma had a consistently elevated male-to-female IRR at 1.4-2.2. Globally, incidence decreased for astrocytic tumours in GEE models (AAPC: -1.66; 95% CI: -3.04 to -0.26) and increased for medulloblastoma (AAPC 0.66; 95% CI: 0.19-1.14), ependymal tumours (AAPC: 1.49; 95% CI: 1.49; 95%: 0.69-2.30), glioma of uncertain origin (AAPC: 4.76; 95% CI: 1.17-1.14) and other embryonal tumours (AAPC: 3.58; 95% CI: 2.03-5.15). Regional variation in incidence trends was observed. Countries moving from lower to higher Human Development Index (HDI) over time did not appear to drive observed incidence trends. Conclusions: Epidemiologic and molecular studies on underlying mechanisms for changes in the global incidence of CNS tumours are necessary.