Cancer Cluster Investigations: Review of the Past and Proposals for the Future

International Journal of Environmental Research and Public Health (Impact Factor: 2.06). 02/2014; 11(2):1479-99. DOI: 10.3390/ijerph110201479
Source: PubMed


Residential clusters of non-communicable diseases are a source of enduring public concern, and at times, controversy. Many clusters reported to public health agencies by concerned citizens are accompanied by expectations that investigations will uncover a cause of disease. While goals, methods and conclusions of cluster studies are debated in the scientific literature and popular press, investigations of reported residential clusters rarely provide definitive answers about disease etiology. Further, it is inherently difficult to study a cluster for diseases with complex etiology and long latency (e.g., most cancers). Regardless, cluster investigations remain an important function of local, state and federal public health agencies. Challenges limiting the ability of cluster investigations to uncover causes for disease include the need to consider long latency, low statistical power of most analyses, uncertain definitions of cluster boundaries and population of interest, and in- and out-migration. A multi-disciplinary Workshop was held to discuss innovative and/or under-explored approaches to investigate cancer clusters. Several potentially fruitful paths forward are described, including modern methods of reconstructing residential history, improved approaches to analyzing spatial data, improved utilization of electronic data sources, advances using biomarkers of carcinogenesis, novel concepts for grouping cases, investigations of infectious etiology of cancer, and "omics" approaches.

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Available from: Donald R Mattison, Mar 11, 2015
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    ABSTRACT: Objective: To evaluate the association between childhood leukemia and residential proximity to nuclear power plants (NPP). Methods: We performed a systematic review by searching the MEDLINE database for published studies of childhood leukemia incidence and proximity to NPP. The primary analysis included children <15 years of age living within 25 km of a NPP, and the secondary analysis focused exposure of children <5 years of age living within 5 km of such facilities. Results: A meta-analysis including eight studies (1,665 cases) of childhood leukemia within 25 km of NPPs produced a pooled estimate of 1.00 (95% confidence interval (CI) = 0.95-1.05). A secondary analysis of a subset of three case-control studies (53 cases) examining the risk in children <5 years of age within 5 km of a NPP produced a meta-estimate of 1.45 (95% CI = 0.74-2.86), and an analysis of the same parameters using four studies (76 cases) from ecological/cohort studies generated a significantly elevated pooled estimate of 1.33 (95% CI = 1.05-1.68). Conclusion: Meta-estimates for ecological/cohort and case-control studies did not provide evidence of an increase in leukemia incidence in children <15 years of age living <25 km of a NPP. A subset of studies including children <5 years of age living <5 km from a NPP produced significantly elevated estimates for ecological/cohort studies. Continuing to undertake large-scale studies of populations surrounding nuclear facilities is encouraged to refine potential risks and better understand methodological nuances.
    No preview · Article · Oct 2015 · Journal of Cancer Policy