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World J Clin Oncol. Aug 10, 2014; 5(3): 539-545
Published online Aug 10, 2014. doi: 10.5306/wjco.v5.i3.539
Inflammatory breast cancer clusters: A hypothesis
Paul H Levine, Salman Hashmi, Ashley A Minaei, Carmela Veneroso
Paul H Levine, Salman Hashmi, Ashley A Minaei, Carmela Veneroso, Department of Epidemiology and Biostatistics, The George Washington University School of Public Health and Health Sciences, Washington, DC 20037, United States
Ashley A Minaei, University of Washington School of Medicine, Seattle, DC 98195, United States
Author contributions: Levine PH coordinated the study, prepared and finalized the manuscript; Hashmi S obtained information for the infectious agents portion of the manuscript, performed an extensive literature search of relevant papers, drafted part of the manuscript; Minaei AA obtained information on the carcinogenic chemical exposure relevant to the paper and drafted the relevant part of the paper; Veneroso C reviewed and edited all of the sections of the paper, made substantial improvements in the final version, and contributed important references and details for the manuscript.
Correspondence to: Paul H Levine, MD, Department of Epidemiology and Biostatistics, The George Washington University School of Public Health and Health Services, 950 New Hampshire Avenue NW, 5th Floor, Washington, DC 20052, United States. paulhlevine@earthlink.net
Telephone: +1-202-9945330 Fax: +1-202-9940082
Received: January 15, 2014
Revised: March 18, 2014
Accepted: April 25, 2014
Published online: August 10, 2014
Processing time: 198 Days and 9.6 Hours
Abstract

Cancer clusters have long been a focus of interest because of the possibility of identifying etiologic agents. Only on rare occasions, however, have such cluster investigations been successful. One major difficulty in cluster investigations, particularly in the area of breast cancer, is the long latent period. There have been a number of publications providing a discouraging picture regarding cancer cluster investigations. The possibility of learning from a cluster investigation, however, is greatly increased if the cancer involved is relatively rare and if it has a short latent period. Inflammatory breast cancer (IBC) fits these criteria and is worth pursuing because of the strong evidence that environmental factors play a major role. In this report we describe our experience with several clusters and the lessons learned which are now being utilized to improve investigation of future IBC clusters. The first IBC cluster that we evaluated was in 2000, when we were asked to investigate an apparent cluster of IBC in Castro Valley, California where three women in an office setting of 24 people were diagnosed with IBC in a ten month period from May 1999 to March 2000. Our investigation of this striking cluster did not yield a specific trigger for this cluster but it did indicate that the women involved all had at least two IBC risk factors that may well have made them susceptible to getting IBC. We are now investigating another apparent cluster in Texas and are aware of several others requiring careful consideration. We see a need for a consistent protocol for the evaluation of IBC clusters focusing on the laboratory investigation of environmental triggers, primarily infectious agents and chemical carcinogens.

Keywords: Inflammatory breast cancer; Environmental; Toxins; Infectious agents

Core tip: Cancer clusters are of interest because of the possibility of identifying etiologic agents. Such cluster investigations have been successful rarely. One major difficulty in the cluster investigations, particularly in the area of breast cancer, is the long latent period. The possibility of learning from a cluster investigation is greatly increased if the cancer is relatively rare and has a short latent period. Inflammatory breast cancer fits these criteria and is worth pursuing because of the strong evidence that environmental factors play a major role. In this report we describe our experience with several clusters and the lessons learned.