Do Clusters of Leukemia and Lymphoma Provide Evidence for an Infectious Cause?
In this issue of the Journal, Heath (1) presents a detailed account of investigations into eight clusters of childhood leukemia and lymphoma carried out by the US Centers for Disease Control and Prevention (CDC) during the 1960s and 1970s. The clusters, chosen for characteristics suggestive of an infectious etiology, were selected from 50 such investigations undertaken during this time period. Heath concludes that indicators of interpersonal contact suggest that infectious disease underlies the etiology of childhood leukemia and lymphoma. Do clusters really provide such evidence? A cluster is an excess incidence of related health events occurring at the same place, the same time, or (more usually) both. The difficulties involved . . .
