Disease Cluster Investigation Program

The purpose of this program is to assess residents' reports of environmentally related disease cluster concerns, such as cancer, that may require public health interventions. The Centers for Disease Control and Prevention (CDC) defines a "cluster" as an unusual grouping, real or perceived, of health events that are grouped together in time and space and that are reported to a health agency.

Highlighted Facts

  • Cancer is a common illness with 1 in 3 people in the United States developing cancer in their lifetime. The risk of cancer increases with age. Cases among older persons are less likely to be classified as a cancer cluster as defined by the CDC.
  • Length of time at residence must be long enough to determine if exposure to hazards may be related to the adverse health outcomes.
  • Some diseases, especially cancer, require a long latency period (latency for childhood cancer may be shorter than for adults).
  • Disease cases that occurred among people that are no longer living may not be helpful in linking the hazard to disease because of the lack of information on exposure and because of other unknown factors, such as lifestyle.
  • Multiple disease diagnoses in a specific area are usually the result of a variety of risk factors instead of a single environmental or genetic factor
  • Documented health outcomes and hazard exposure, latency period, date of the exposure, and type of exposure must be available to establish a disease cluster.

Defining Environmental Disease Clusters

To establish an environmentally related disease cluster, the following evidence must be present:

  • Verified disease(s) or health outcomes(s) of concern
  • Determination of region and time period of disease occurrence
  • A source of environmental exposure
  • A known connection between the hazard and the disease or health outcome of concern
  • Statistical Testing confirming the cluster of disease(s) or health outcomes(s)


The LTR was created to record cancer incidence throughout the state and is among the leading cancer registries for its quality and completeness of data.