What term describes a greater-than-expected number of cancer cases within a defined group?

• A. Cancer cluster
• B. Carcinogen
• C. Centers for Disease Control and Prevention (CDC)
• D. National Institutes of Health (NIH)

Answer: (A)

A cancer cluster is the term that fits this description. It refers to a greater-than-expected number of cancer cases in a defined group, such as a geographic area, workplace, or a specific time period, compared to what would be expected based on population size and demographics. The idea is not just a handful of cases, but a statistically unusual concentration that prompts public health investigation to explore potential environmental exposures, genetic factors, or other causes—and sometimes to determine that the excess is due to chance.

This differs from a carcinogen, which is any substance or agent that can cause cancer, not a pattern of how many cases occur. It also isn’t about organizations like the CDC or NIH, which are federal agencies and research bodies, not terms describing the number of cancer cases in a group.