Facts about cancer clusters:
— Clusters occur when there are more cancer cases than statistically expected in a specific area over a certain time.
— They're typically limited to one type of cancer or a rare form of it, or a type of cancer that strikes people at an age when they usually don't get that kind of malignancy.
— Verifying a cluster exists is difficult because cancer comes in many forms and has many causes. It also can develop quickly or over several years. And cancer is so common that 1 of every 3 people will develop it.
— Many suspected clusters turn out not to be a true cluster. Most occur by chance.
— The causes of childhood cancers are mostly unknown.
— About 27 children under age 15 are diagnosed with cancer in the U.S. every day.
— Even after a cluster is confirmed, a cause for it usually isn't found.
Sources: U.S. Centers for Disease Control and Prevention, National Cancer Institute, American Cancer Society