Leukemia Cluster Information

Leukemia Cluster Information for Cochise County

A Community Disease: Overview
In August of 2001, physicians at the Arizona Cancer Center recognized a number of childhood leukemia patients as being from the Sierra Vista area, and notified the Arizona Department of Health Services (ADHS).  For the next five years, the Cochise County Health Department worked with ADHS, local medical professionals, university and cancer researchers and finally the Center for Disease Control and Prevention (CDC) to bring about an investigation into what was being labeled a “cancer cluster”. A disease cluster is the occurrence of a greater than expected number of cases of a particular disease within a group of people, a geographic area, or a period of time.

In that time, the County Health Department and ADHS partnered with several agencies and individuals including local elected officials ADHS, Arizona Department of Environmental Quality, representatives from Ft. Huachuca, and Congressman Jim Kolbe to ensure appropriate questions were asked, that proper steps were taken to address the issue without raising community anxiety, and that care was taken to protect the privacy of the affected families.

This effort culminated with a voluntary local biosampling of families in the spring of 2005. Participants included families with children diagnosed with leukemia and selected comparison families with children who did not have leukemia. The results would become part of the CDC cancer databank to be used for future research about leukemia. This is important because so little is known about childhood leukemia.

For information on the Biosampling investigation process click here.

Biosampling: Testing for the Future
Thanks to a concerted effort by local elected officials, Cochise County garnered the assistance and support of a CDC research team as well as ongoing support from ADHS. In May 2005, under the direction of Cochise County Health Department, the biosampling team began biological sampling for analysis at CDC labs. Biosampling involves taking blood, urine and buccal (mouth) cell samples from the patients, their immediate family members, and randomly selected comparison families who do not have leukemia.  In addition to the samples, each participant answered a brief questionnaire covering medical history, personal habits, and exposures to possible toxins.

Bio-sampling is a long, careful process which is governed by strict CDC guidelines (click here for the "Protocol for Biosampling Children with Leukemia [Acute Lymphocytic and Acute Myelocytic Leukemias] plus a Comparison Population in Sierra Vista, Arizona."  )   The reasons the process is so carefully monitored include:

  • a desire to ensure consistent, ethical scientific practice;
  • the need to ensure consistent and useful results; and,
  • perhaps most importantly, to ensure the dignity and privacy of participants.

Sierra Vista Results
The results of the Sierra Vista study were revealed to the families and the general public on November 30, 2006. The study did not link an environmental cause for the cluster; however the researchers did identify a variant form a gene known as SUOX, in children who have been diagnosed with leukemia.

Several members of the CDC traveled to Sierra Vista to meet with the families who participated to confidentially discuss their results. Following these meetings, CDC and ADHS personnel met with the public in a community availability session to show results of the particular findings of levels of metals, pesticides, and volatile organic compounds such as benzene and styrene. More than 128 environmental substances were tested and the investigation revealed nothing of medical significance.

Also presented and discussed was the discovery of a variation in the gene known as SUOX which tells the body how to produce sulfite oxidase, which changes harmful compounds to less harmful ones. The variant was present in children with and without leukemia prompting the CDC personnel to conduct more focused research on the role of SUOX.

Copies of the complete CDC Report: Biosampling Case Children with Leukemia (Acute Lymphocytic and Myelocytic Leukemia) and a Reference Population in Sierra Vista, Arizona can be found at www.cdc.gov/nceh/clusters/sierravista.

Throughout the course of this issue, Cochise County Health Department has worked closely. It was this level of concern that prompted local officials, with support from Rep. Jim Kolbe, to request assistance from the Centers for Disease Control in September of 2003.  As a result, a team of investigators from CDC will assist Cochise County Health Department with biosampling of the families where leukemia has been diagnosed, as well as "control" families who do not have a leukemia diagnosis.

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