Is there a common aetiology for certain childhood malignancies? Results of cross-space-time clustering analyses.

We previously demonstrated significant space-time clustering amongst cases of childhood leukaemia (in particular acute lymphoblastic leukaemia (ALL)), central nervous system (CNS) tumour (especially astrocytoma), soft tissue sarcoma and Wilms' tumour. We hypothesised that there may be common aetiological mechanisms between some of these diagnostic groups. To test this hypothesis we analysed for cross-space-time clustering between these diagnostic groups, using population-based data from north-west England. Data were examined by a second-order procedure based on K-functions. Reference points in time and space were dates and addresses at birth and diagnosis. The results showed statistically significant (P < 0.05) cross-clustering between cases of leukaemia and CNS tumour and between cases of ALL and astrocytoma. There was no statistically significant cross-clustering of Wilms' tumours and soft tissue sarcomas with any other malignancy. In conclusion, these findings are consistent with common, possibly infectious, aetiological mechanisms for childhood leukaemia (particularly ALL) and CNS tumours (particularly astrocytoma).