According to seer.cancer.gov 234,000 women get breast cancer a...

According to seer.cancer.gov 234,000 women get breast cancer a year so you are working off 50% of this figure to arrive at your approx 100,000. That is not how I would derive the size of the market. This is a preventative test designed to assess a women's 'risk' of breast cancer it is not a treatment. To assume that the number of cases of women who contract breast cancer annually is proportionally related to the number of people that may take up a preventative diagnostic test is erroneous. Your reasoning is sound but not necessarily your assumptions