Further clues concerning the aetiology of childhood central nervous system tumours

Previously, we reported space-time clustering and seasonal variation in childhood central nervous system (CNS) tumours for the period 1954-1998. These previous studies provided evidence that infections may be involved in aetiology. To determine whether there were also localised spatial factors involved in aetiology we analysed the geographical distribution of CNS tumours in children aged 0-14 years using Manchester Children's Tumour Registry (MCTR) data for the period 1976-2000. Specifically, the Potthoff-Whittinghill test for spatial clustering was applied and Poisson regression was used to analyse the relationship between incidence rates and small-area population density, ethnic composition and deprivation index. No relationships were seen for all CNS tumours together and only a few for the subgroups. The previous findings of space-time clustering and seasonal variation, involving astrocytoma and ependymoma, together with the lack of spatial clustering and ecological relationships for these tumours provide evidence that astrocytoma and ependymoma may be associated with a highly mobile transient aetiological agent. An example of such an agent is an infection that occurs in mini-epidemics.