In measuring breast cancer incidence, which group of women is counted in the numerator?

The correct answer focuses on the specific point in time for which breast cancer incidence is being measured, which is defined as newly diagnosed cases within a given timeframe. In this context, the numerator includes women diagnosed with breast cancer during a particular period, making it essential to pinpoint those who have been newly identified as having the disease.

By selecting women diagnosed with breast cancer in January 2015, this group accurately reflects new cases inclusive in the statistics for that year, thus enabling a proper calculation of breast cancer incidence during that specified timeframe. This ensures that the data collected is relevant and provides insights into trends in incidence rates.

The other choices either represent cases from a time outside of the measurement window or include individuals who are not newly diagnosed. For example, counting women with breast cancer from January 1, 2013, to January 1, 2014, includes cases that may not be newly diagnosed within the specific year being studied. Similarly, including all women in Texas who currently have breast cancer does not limit the count to newly diagnosed cases, which dilutes the accuracy of the incidence measurement. Lastly, counting the total number of women living in Texas does not pertain to incidence at all, as it ignores any information about breast cancer diagnoses.