The purpose of this study is to determine the effectiveness of Estradiol treatment for
advanced breast cancer that is hormone receptor negative and Her2/neu negative. The study
will also use tumor tissue from your original diagnosis or from a biopsy you may have had for
your cancer to look at hormone receptors in the lab. The tissue left over from your previous
surgery or a previous biopsy will be used for research tests to check whether a different
estrogen receptor (estrogen receptor beta) is seen in the tumor and if that makes estrogen
work better.