10,155
Views
34
CrossRef citations to date
0
Altmetric
Review Article

Cancer clusters in the USA: What do the last twenty years of state and federal investigations tell us?

, , &
Pages 474-490 | Received 04 Jan 2012, Accepted 09 Mar 2012, Published online: 21 Apr 2012
 

Abstract

Background: Cancer clusters garner considerable public and legislative attention, and there is often an expectation that cluster investigations in a community will reveal a causal link to an environmental exposure. At a 1989 national conference on disease clusters, it was reported that cluster studies conducted in the 1970s and 1980s rarely, if ever, produced important findings. We seek to answer the question: Have cancer cluster investigations conducted by US health agencies in the past 20 years improved our understanding of cancer etiology, or informed cancer prevention and control?

Methods: We reviewed publicly available cancer cluster investigation reports since 1990, obtained from literature searches and by canvassing all 50 states and the District of Columbia. Investigations were categorized with respect to cancer type(s), hypothesized exposure, whether perceived clusters were confirmed (e.g. by elevated incidence), and conclusions about a link between cancer(s) of concern and hypothesized environmental exposure(s).

Results: We reviewed 428 investigations evaluating 567 cancers of concern. An increase in incidence was confirmed for 72 (13%) cancer categories (including the category “all sites”). Three of those were linked (with variable degree of certainty) to hypothesized exposures, but only one investigation revealed a clear cause.

Conclusions: It is fair to state that extensive efforts to find causes of community cancer clusters have not been successful. There are fundamental shortcomings to our current methods of investigating community cancer clusters. We recommend a multidisciplinary national dialogue on creative, innovative approaches to understanding when and why cancer and other chronic diseases cluster in space and time.

Acknowledgments

The authors are grateful to the state representatives who took the time to both speak with us and to search their records for available reports of cluster investigations. We could not have conducted this research without their assistance. This research was supported by the Chlorine Chemistry Division of the American Chemistry Council (ACC). ACC was not involved in the design, collection, management, analysis, or interpretation of the data; or in the preparation or approval of the manuscript.

Declaration of interest

This research was supported by the Chlorine Chemistry Division of the American Chemistry Council. The authors’ affiliations are as shown on the cover page. The authors have sole responsibility for the writing and content of the paper. J.S.L. and M.G. consult to both government and industry.