Cancer cluster suspicions usually arise when members of the general public report that their family members, friends, neighbors, or coworkers have been diagnosed with the same or related cancers. State or local health departments will investigate the possibility of a cancer cluster when a claim is filed.[3] In order to justify investigating such claims, health departments conduct a preliminary review. Data will be collected and verified regarding: the types of cancer reported, numbers of cases, geographic area of the cases, and the patients clinical history.