Four adults in one neighbourhood are diagnosed with cancer and residents are alarmed, but nobody knows how many cases would be usual there. Which term fits?

1. Calling something an outbreak or epidemic means claiming there are more cases than expected. 2. Here the expected number is unknown, so that claim cannot be made yet. 3. An aggregation of cases in one area over one period, without knowing whether the number exceeds expectation, is a cluster. 4. Four cancers among neighbours may well sit inside the expected level once population size and cancer type are considered. 5. Pandemic requires spread across several countries or continents, which plainly does not apply. _Source: CDC Principles of Epidemiology in Public Health Practice, 3rd Edition, section Step 2 Establish the Existence of an Outbreak_