CONTEXT: In fiscal year 2019, the Department of Health and Human Services (DHHS) received an appropriation from Congress specifically to update guidelines for investigating community cancer concerns. This resulted in the DHHS directing the Centers for Disease Control and Prevention (CDC) to fulfill this responsibility. PROGRAM: The CDC and the Agency for Toxic Substances and Disease Registry (ATSDR) provide guidance to state, tribal, local, and territorial (STLT) health departments and play important roles in supporting STLT programs in addressing community cancer concerns. IMPLEMENTATION: The updated guidelines offer enhancements addressing limitations and challenges regarding the process for investigating cancer clusters as expressed by STLT programs responsible for responding to inquiries and by communities impacted by unusual patterns of cancer. Additionally, the updated guidelines offer new tools and approaches associated with scientific advancements. Issues associated with improving communications and community engagement were a priority. Details in the updated guidelines provide suggestions for building and maintaining trust; provide resources via additional tools, templates, and methodology to facilitate sharing of information; provide suggestions for identifying agency and community points of contacts; and provide suggestions for establishing a community advisory committee. CONCLUSION: Enhancements to the previous guidelines were included to address advancements in statistical approaches and methods for understanding exposure pathways and also to respond to limitations described in the previous guidelines. Furthermore, these enhancements ensure communities have a voice in the process and offer methods to enhance transparency throughout the investigative process. Ultimately, the 2022 Guidelines are designed to ensure that community engagement, community input, and communication remains paramount to the process of assessing unusual patterns of cancer and environmental concerns.

This report augments guidelines published in 1990 for investigating clusters of health events (CDC. Guidelines for investigating clusters of health events. MMWR 1990;39[No. RR-11]). The 1990 Guidelines considered any noninfectious disease cluster, injuries, birth defects, and previously unrecognized syndromes or illnesses. These new guidelines focus on cancer clusters. State and local health departments can use these guidelines to develop a systematic approach to responding to community concerns regarding cancer clusters. The guidelines are intended to apply to situations in which a health department responds to an inquiry about a suspected cancer cluster in a residential or community setting only. Occupational or medical treatment-related clusters are not included in this report. Since 1990, many improvements have occurred in data resources, investigative techniques, and analytic/statistical methods, and much has been learned from both large- and small-scale cancer cluster investigations. These improvements and lessons have informed these updated guidelines. These guidelines utilize a four-step approach (initial response, assessment, major feasibility study, and etiologic investigation) as a tool for managing a reported cluster. Even if a cancer cluster is identified, there is no guarantee that a common cause or an environmental contaminant will be implicated. Identification of a common cause or an implicated contaminant might be an expected outcome for the concerned community. Therefore, during all parts of an inquiry, responders should be transparent, communicate clearly, and explain their decisions to the community.