Cancer Clusters
The definition of a cancer cluster has been updated. Please visit https://www.cdc.gov/nceh/cancer-environment/index.html for more information.
State and local health agencies can sometimes use state cancer registry information to look at the number of cancers in a community compared to the number in the state. Comparisons are made within groups of people of the same age, sex, and race because these are some known factors that influence the likelihood of getting cancer. A finding of more cancers than expected in an area does not mean there is a single cause or risk that can be identified or addressed. The finding can be due to chance, known risk factors, unknown causes, and other reasons. Usually more involved follow-up studies are needed, but even then, the cause of the possible cancer cluster may not be identified.