摘要：Cancer cluster investigations need to address the disconnect between traditional public health approaches and human needs. Cancer cluster investigations often magnify fear and uncertainty because they rarely find a definitive environmental cause. Traditional approaches emphasize population-level data analysis and undervalue active listening. Because few studies have explored active listening in cancer cluster investigations, we conducted a descriptive oral history case study of a Frederick, Maryland, investigation. We interviewed 12 community members and 9 public health professionals about the investigation of a perceived cancer cluster. Many believed it was linked to environmental contamination at Fort Detrick, a local US Army base. We propose enhanced active listening that seeks out peoples’ perspectives, validates their concerns, and engages them in the investigative process. A cancer cluster is “an excess number of observed cancer cases or deaths by place and time.”1(p811) Every year in the United States, more than 1000 reports of suspected cancer clusters are made to public health authorities. 2,3 An estimated 70% to 95% of these reports are resolved through a phone conversation with the informant or a letter from the state. 2 Most reports do not require investigation because they can be explained through education, for example, by describing how common cancers are (people have “a one in three lifetime probability” of receiving a cancer diagnosis) and how risk for cancer increases with age. 4 For the reports that do warrant a follow-up investigation, typically cancer incidence in the population of interest is compared with statewide cancer rates. In a small percentage of these investigations, the number of cancer cases exceeds the expected number for the population of interest within a specified period of time. 5 Chance, however, can explain a significant number of these suspected clusters. 6 Of the relatively small number of cluster investigations conducted, very few, if any, are able to establish a clear environmental cause. A review of 428 suspected cancer cluster investigations in the United States evaluating 567 cancers of concern from 1990 to 2011 found that only 1 was linked to a clear cause—and that was occupation related. Asbestos-exposed shipyard workers in South Carolina experienced an increased rate of pleural cancers. 7 Goodman et al. concluded, “It is fair to state that extensive efforts to find causes of community cancer clusters have not been successful.”7(p474) A prior review of 108 cancer cluster investigations by the Centers for Disease Control and Prevention (CDC) from 1961 to 1982 found that no clear cause was determined in any of the clusters. 8 (pS43) For these reasons—and because of finite resources—public health officials must consider other needs before embarking on cancer cluster investigations that will be difficult and unlikely to produce definitive results. 5,9 Indeed as a 1990 editorial in The Lancet noted, “The cluster alarm can become the epidemiologist’s nightmare.” 10 (p717) However, people who have lost loved ones to what they believe is a cancer cluster have a very different definition of “nightmare.” They want to know what caused the suspected cluster, who is at fault, and how they can protect themselves and their loved ones in the future. 1 Confronted with unexplained and unseen threats, community members often believe immediate attention and action are needed. 9 As Trumbo et al. noted, Because many factors can create the appearance of a cluster when the existence of a cluster cannot be confirmed, health officials who respond to cluster inquiries must face the extra challenge of addressing public concerns about a topic fraught with scientific uncertainty and a great deal of fear. 11 (p161) In its original 1990 guidelines on cluster investigations, the CDC noted, “From a public health perspective, the perception of a cluster in a community may be as important as, or more important than, an actual cluster.”4(emphasis added) Many people are familiar with movies such as A Civil Action and Erin Brockovich, which propagate the impression that toxic exposures are “a major cause of human cancers.” 5 (p273) Local media coverage can feed perceptions that a cluster exists, increasing fear about cancer risks and concerns about other impacts such as reduced property values. When investigative results are not immediate or to their liking, residents can feel frustrated and angry. To them, proving a cluster exists and finding its cause are worth any expense. As 1 cancer survivor told us, “They say there’s not time or money to do a proper job. Believe me there’s not time or money to have cancer” (cancer survivor, oral communication, July 2012).
