What should a public health nurse explain about calculating the incidence rate of breast cancer?

The concept of incidence in public health refers specifically to the number of new cases of a disease occurring in a defined population over a specific period of time, and it is crucial that this calculation only includes individuals who are at risk for developing the disease. This means that when calculating the incidence rate of breast cancer, public health professionals only consider individuals who do not have breast cancer at the start of the observation period but are at risk of developing it.

Focusing on those at risk avoids inflating the incidence rate with data from individuals who already have the disease or are not susceptible, which would skew the understanding of how frequently new cases arise in the population. Therefore, to accurately reflect the occurrence of new cases, it is essential to include only those individuals who could potentially develop breast cancer.

The other options do not align with the definition of incidence:

• Including both symptomatic and asymptomatic individuals is not accurate since incidence concerns only new cases among those at risk.

• Reflecting the total number of breast cancer cases confuses incidence with prevalence, which considers both existing and new cases.

• Dividing total cases by the population does not account for the specificity needed in identifying only the at-risk population for an accurate incidence rate calculation.