Spatial clustering of childhood cancers in the Denver Metroplex

Scott Ferson

Supported by Radian Corporation, with funding from Electric Power Research Institute (EPRI)

Project description

        Although we could detect no spatial clustering of childhood cancers at the finest resolution of individual cases and controls, analysis with aggregated data using census information detected statistically significant spatial clustering. The intensity (and significance) of the spatial clustering was even stronger at the level of entire cities in the Denver metroplex. The principal finding is that, when the locations of childhood cancers are aggregated into area/frequency data, statistical tests reveal significant spatial clustering. This conclusion is robust in the sense that it is independent of many details of the analysis and the data and seems to persist over spatial resolutions ranging from the scale of a city to that of a census tract. This confirms the finding that there is strong spatial inhomogeneity in childhood cancer incidence across the region. The inhomogeneity cannot be removed simply by accounting for changes in the population density of children. This observation of clustering of childhood cancers has several important ramifications for the study of this cancer's phenomenology. The findings call into question many of the other statistical procedures already conducted on this data set that have assumed spatial homogeneity of disease etiology or incidence. Although often unstated, such an assumption is very common and probably affects many if not the majority of the most prominent conclusions that have been made about the Denver cancer data.

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