To undertake the process of updating the 2013 Guidelines, the NCEH/ATSDR Director established a team with subject matter experts from NCEH and ATSDR to develop a plan for gathering input to identify shortcomings and frustrations with the 2013 Guidelines and offer enhancements for best practices when examining unusual patterns of cancer and environmental concerns. The purpose of this paper is to discuss these changes with respect to community engagement, from start to finish of the process.

The process to obtain input for updating the guidelines was an extensive, multipronged approach that included convening a CDC/ATSDR Internal Steering Committee, holding an expert panel forum, holding a stakeholder meeting, conducting a survey of STLT health departments, conducting a series of focus groups with STLT partners, and another series of focus groups with representatives of communities impacted by cancer cluster concerns. The Internal Steering Committee included subject matter experts from ATSDR, NCEH, the Division of Cancer Prevention and Control, and the National Institute for Occupational Safety and Health. Through regular meetings, the committee provided input on the information gathering efforts and reviewed drafts of the revised guidelines. An expert panel forum was held in September 2019. The expert panel forum gathered participants with expertise in state and local health cancer cluster investigations, epidemiology, risk communication, cancer registries, and pediatric environmental health. The experts discussed the following topics: geospatial methods for investigating cancer clusters, statistical significance in public health investigations, mutational signatures of environmental exposures in cancer, the importance of etiological factors, environmental exposures and pediatric cancer, and risk communication and community involvement. Additional experts provided feedback during a stakeholder meeting that took place in April 2021. Stakeholders representing pediatric environmental health; academia; county, city, state, and territorial health departments; and pediatric cancer advocates met and shared their thoughts on revising the 2013 Guidelines.

CDC/ATSDR distributed an electronic survey with a 100% response rate of all state health departments with representatives providing input from departments of environmental health, chronic disease programs, and cancer registries. The goal of the survey was to solicit feedback from STLT public health agencies on current approaches; best practices, barriers, and facilitators; and capacity for addressing cancer cluster inquiries. A series of focus groups with health department partners was conducted with similar representation from cancer registries, environmental health, health communicators, and community engagement specialists subsequent to the survey to collect more detailed information about how STLT public health agencies address cancer cluster inquiries, how STLT public health agencies determine when to proceed with a cancer cluster investigation, communication capabilities and resources, best practices, and overall feedback on the 2013 Guidelines. From the STLT survey, STLT focus groups, and a scan of traditional and social media community focus group members were identified. In addition to seeking input from community members and the public through focus groups and a stakeholder meeting, two federal register notices (FRN) were published. The first FRN⁸ was published in May 2019 and open for public comment for 60 days. This FRN invited public comment on strengths and gaps of the 2013 Guidelines and other factors CDC/ATSDR should consider when updating the 2013 Guidelines. The second FRN⁹ was published in May 2022, and was open for 60 days for public comment, also. The second FRN requested feedback on the strengths and limitations of the revisions proposed in the drafted revised guidelines. Feedback from reports developed by the Association of State and Territorial Health Officials¹⁰ and the Council of State and Territorial Epidemiologists¹¹ were also incorporated.

These activity were reviewed by CDC and conducted consistent with applicable federal law and CDC policy (45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. §241[d]; 5 U.S.C. §552a; 44 U.S.C. §3501 et seq.).

Quantitative and qualitative analysis of these collective inputs received from state health officials, community members, and advocates made clear that the 2013 Guidelines (and local investigative protocols based upon those guidelines) had limitations. Overarching themes emerging from STLT partner feedback suggested reconsideration of the definition of a cancer cluster and broader consideration of environmental factors when addressing cancer inquiries. Feedback from subject matter experts and STLT partners suggested reconsidering the role of statistical significance, coinciding with the American Statistical Association’s statement on P-values.¹²

Community members and advocates also noted frustration in their having to be responsible for identifying unusual patterns in their communities and bringing these issues to the attention of government officials. Similarly, community and advocate input highlighted overall dissatisfaction with the process when investigations ended following cursory reviews of cancer data, and notably, that statistical significance alone was the primary driver of any further evaluation of community concerns.

Beyond statistical and methodological challenges, the feedback from all partners and stakeholders highlighted the importance of meaningful and effective communication.¹ STLT partners stressed the importance of plain language and clear communications, a consistent message, and being transparent throughout the process. They also mentioned the importance of engaging and working with the community from the beginning to the end of a response. Similarly, stakeholders and communities impacted by cancer concerns indicated the importance of proactive and meaningful communications to building relationships and trust. They also shared the importance of staff responsible for engaging with the community having training and proficiency in communication and strong interpersonal skills. While each community inquiry may present unique circumstances and may require varying levels of community engagement,^13,14 the input received reinforced the importance of early interactions between community members and health officials to establish trust¹⁵ and credibility of the investigative process.

The result of the inputs received led to the December 2022 publication of the CDC/ATSDR Guidelines for Examining Unusual Patterns of Cancer and Environmental Concerns¹⁶ (hereafter referred to as the 2022 Guidelines). The 2022 Guidelines address limitations of the 2013 Guidelines by:

Revising the definition of a cancer cluster to consider etiologically related cancer cases.

Much feedback was received regarding the definition of a cancer cluster. While opinions differed on some of the specifics for suggested revisions, most inputs called for a change. In particular, the overall feedback indicated the need to expand the previous definition, which was focused primarily on one type of cancer. We also heard that the term “cancer cluster” can be confusing and invoke negative emotions. Therefore, a recommendation was made to clarify the definition by including mention of potential etiology or associations between the specific cancer type and known environmental contaminants. Some state health department representatives suggested that since environmental concerns are often the impetus related to concerns over cancer in a community, expanding the title and offering guidance to respond to environmental concerns raised might be helpful in providing the community with some answers even if answers to cancer concerns may not be available.

Based on this feedback, the title and the text of the 2022 Guidelines were revised to consider unusual patterns of cancer over the term cancer cluster and to include environmental concerns in both the title and as part of the assessment approach. The 2022 Guidelines still refer to clusters; however, the 2022 Guidelines recognize that while not all unusual patterns of cancer are clusters some may warrant further examination.

As reported in the STLT survey results,¹ the majority of STLT health departments indicate proactive review of cancer registry data is standard practice. Subject matter experts also strongly recommended developing a more proactive monitoring approach. Community members and advocates emphasized a desire for STLT officials to review cancer data routinely to identify problems reducing the burden on them to alert officials of unusual patterns. They expressed a desire for a better system of watchfulness. Given community input and the results from the survey, the 2022 Guidelines recommend in addition to responsive review the proactive review of cancer registry data with a commitment to continue reviewing data as new years of data become available.

While many states reported conducting routine surveillance activities, we also recognized that for some states the resources are not available to do this routinely. To better address resource concerns associated with proactive surveillance, the CDC’s Environmental Health Tracking Program worked with the Division of Cancer Prevention and Control, some states environmental health departments, and cancer registry staff to calculate and display standardized incidence ratio measures with cancer registry data. The measures are available on the National Environmental Public Health Tracking Network Data Explorer¹⁷ and can be viewed by state health departments and the public. These efforts allow for more data-informed decisions and routine monitoring of cancer data. Additionally, with the availability of these measures, consultation and collaboration among environmental health, cancer registry, and cancer control staff may be prompted. In some cases, epidemiologic follow up may be warranted and in other cases suggestions for ongoing monitoring of a cancer over time in a specific area might be prudent.

When STLT respondents were asked to suggest best practices for communicating with the public about potential cancer clusters, respondents stressed the importance of plain language and clear communications, a prompt response, a consistent message, as well as being transparent throughout the inquiry and investigation process. Many state agency staff discussed the importance of listening to the constituent or inquirer and trying to meet in-person or discuss via phone when possible. Therefore, even before any actions are taken by a STLT health official, the 2022 Guidelines describe the importance of communicating with and engaging communities to establish and maintain trust and new phases were added sharing recommendations for engaging and communicating with impacted communities.

As mentioned previously, community participants and advocates desired more transparency from public health agencies about potential environmental contamination or hazards in their communities and urged government officials to notify the community if there are any unusual patterns of cancer identified. A repeated message was a request to be engaged and to not feel dismissed.

Given this feedback, the 2022 Guidelines discusses the need to establish a community engagement plan. A community engagement plan can assist with establishing a strong relationship between the community and the health department. The plan recommends appointing a health department liaison and a community member liaison. The health department liaison may not necessarily be the epidemiologist or scientist leading the assessment or investigation; for example, it could be a communications specialist, a social worker, or a public health nurse. Recommendations are also made to follow up with the inquirer or community liaison on some agreed upon timeline.

Additional feedback from the survey and from the focus groups discussions with STLT partners suggested a standardized intake form would be valuable. Therefore, two new forms have been included along with the 2022 Guidelines. The intake form suggests collection of information about the cancer of concern, the environmental concerns if any are proposed, and the location. Templates are available to easily upload to REDCap, use in EpiInfo, use in Excel, or upload the data dictionary to other database software. In the future, CDC/NCEH would like to ask for de-identified data about the inquiries received by states be shared with CDC/NCEH. This will be the first time that CDC/ATSDR will be able to more consistently understand the extent and number of inquiries and the resource impacts on the states conducting this work. It would enable CDC/ATSDR to understand types of cancers and environmental areas of concern across the United States with an eye towards identifying national trends. These data may help to connect STLT partners who may be receiving inquiries about similar cancers or environmental concerns, also.

We also heard that having a checklist of activities for addressing inquiries is useful. Simultaneously, we also heard criticisms of the 4-step process. Therefore, the 2022 Guidelines suggest a reformulation of the process that incorporates elements of the 4-step process but also provides additional guidance on actions for further assessment. The decision-making form (Figure 1) and template provide 10 assessment criteria. The guidelines also include a new decision tree (Figure 2).

In summary, moving forward with further assessment can mean a variety of things including reviewing additional data, referring to internal or external partners, doing environmental sampling, or conducting epidemiologic follow up activities. If after reviewing the 10 criteria form there will not be additional assessment, it is recommended to provide a report summarizing the findings and data reviewed. The information from the decision-making form with the 10 criteria can be used to better communicate with the community and provide additional educational materials about the cancer and findings, which STLT partners also reported as standard practice. It is also suggested that the cancer and/or area of inquiry be added to a list for future monitoring through routine surveillance. Alternatively, if the 10 criteria suggest further assessment, ideas are provided of actions for further assessment. Regardless of the action, the 2022 Guidelines highlight and offer recommendations for best practices and resources to establish strong and meaningful engagement and communication with the community.

The updates made to the 2022 Guidelines present an enhanced approach for examining unusual patterns of cancer reflecting the importance of community engagement and clear communication throughout the process of assessing unusual patterns of cancer and environmental concerns. Details include an expanded definition of a cancer cluster and new criteria to consider when examining unusual patterns. New templates, such as the intake form, offer standardized approaches for information collection and offer a streamlined approach to address community cancer and environmental concerns. Moreover, the update provides suggestions for building and maintaining trust to facilitate interactions and to assist in alleviating frustrations experienced by impacted communities in the past. Additional tools, templates, and methodology provide resources for STLT health officials to facilitate sharing of information and enhance transparency throughout the investigative process. Identifying agency and community points of contacts and establishing a community advisory committee are further suggestions to ensure communities have a voice in the process.