Community cancer clusters are viewed quite differently by citizen activists than by epidemiologists. Environmentalists and concerned local residents, for instance, might immediately suspect environmental radiation as the culprit when a high incidence of cancer cases occurs near a nuclear facility. Epidemiologists, in contrast, would be more likely to say that the incidences were “inconclusive” or the result of pure chance. And when a breast cancer survivor, Lorraine Pace, mapped twenty breast cancer cases occurring in her West Islip, Long Island community, her rudimentary research efforts were guided more by hope―that a specific environmental agent could be correlated with the cancers―than by scientific method. When epidemiologists study clusters of cancer cases and other noncontagious conditions such as birth defects or miscarriage, they take several variables into account, such as background rate, i.e. the number of people affected in the general population, cluster size, and specificity (any notable characteristics of the individual affected in each case). If a cluster is both large and specific, it is easier for epidemiologists to assign blame. Not only must each variable be considered on its own, but it must also be combined with others. Lung cancer is very common in the general population. Yet, when a huge number of cases turned up among World War II shipbuilders who had all worked with asbestos, the size of the cluster and the fact that the men had had similar occupational asbestos exposures enabled epidemiologists to assign blame to the fibrous mineral. However, even if a cluster seems too small to be analyzed conclusively, it may still yield important data if the background rate of the condition is low enough. This was the case when a certain cancer turned up almost simultaneously in a half-dozen young women. While six would seem to be too small a cluster for meaningful study, the cancer had been reported only once or twice before in the entire medical literature. Researchers eventually found that the mothers of all the afflicted women had taken the drug diethystilbestrol (DES).