Clustering of childhood acute leukaemia: The EUROCLUS Project.

The EUROCLUS Project is a collaborative endeavour in which incidence data for 13 35 1 cases of childhood leukaemia (CL) diagnosed between 1980 and 1989 in 17 countries were referenced to 26 425 small geographic areas and tested for evidence of spatial clustering. A second objective of EUROCLUS was to determine whether clustering of CL was associated with community demographic features and/or proximity to putative environmental hazards. The results show statistically significant evidence of clustering, but the magnitude is small (extra-Poisson variability = 1.65% of Poisson variability). Patterns of clustering are associated with population density and other demographic features which could indicate variations in opportunity for exposure to common infections. There is no consistent evidence that clusters are associated with proximity to nuclear facilities or other putative environmental hazards.