Disease Clusters: An Overview

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U.S. Department of Health and Human Services
Date published
Aug, 2002
Last updated
25 Jan 2020


The goals of these case studies in environmental medicine are to increase the knowledge of health care providers, especially pediatricians, of the special susceptibilities of children to hazardous substances in the environment and to aid in their evaluation of potentially exposed patients.

After completion of this educational activity, the reader should be able to define a disease cluster, describe the components of the public health department disease cluster investigation, and describe the physician’s responsibility regarding disease clusters.  

For all of these cases, you are the senior partner in a busy suburban primary care practice. In the past 30 days, three of the physicians in your practice have come to you individually to discuss a case of concern.

The cases are outlined below:

  • Case 1: The patient is a 40-year-old second-grade schoolteacher who came in for an annual checkup and breast exam. A mass was noted on her mammogram. The patient is scheduled for stereotactic biopsy. She expressed concerns that three other female teachers in her elementary school have been diagnosed with breast cancer in the 4 years that the school has been open. She is worried that working at the school might have caused all or some of these cases. The elementary school was built in an area that once housed several industrial facilities.
  • Case 2: The family practitioner in the group has a 35-year-old female primigravida in her 10th week of pregnancy with vaginal bleeding. The patient is concerned about the neighborhood where she has lived for 3 years. She recently learned in the past 4 years, six miscarriages in the first trimester have occurred in her neighborhood of 100 women.
  • Case 3: An 87-year-old grandmother of three who came in for her annual checkup had occult blood in her stool and is scheduled for a colonoscopy with biopsy. She mentioned that three of her neighbors from the active seniors club have been diagnosed with cancer in the past 2 years. She is concerned that living in her neighborhood is causing the cancer.

These patients’ concerns and questions seem to have a common theme. You are planning the next physician education conference for the physicians in your practice and would like to discuss disease clusters and pertinent patient education points. Busy clinicians are often expected to respond to patient inquiries about disease “cluster” events. Cluster events are groupings of a particular disorder or a class of disorders, such as potentially related cancers, that appear unusually frequent in a place. Such events pose challenges of interpretation that differ from clinical evaluation of individual patients. Accordingly, the goals of this monograph are to provide clinicians with a framework for discussion of disease clusters.