Additional Study Information: The purpose of this research study is to determine if using a piece of the patient's residual tumor to develop a model of her cancer in mice that lack an immune system (also called an immune-deficient mouse) could help in determining which additional drugs or compounds to which an individual breast tumor is sensitive. The tumor implanted in the mouse is called a patient-derived xenograft model or PDX model. We will also be measuring gene expression from the tumor specimen, collected at time of surgery, in order to select specific targeted medications to test in the PDX models.