On the day prior to surgery, baseline assessments will be repeated (with the exception of menopausal determination and tamoxifen metabolism gene polymorphisms, but with the addition of blood draw for tamoxifen metabolites and E and Z 4-OHT isomer determination). Under unavoidable circumstances, the end of intervention visit will be allowed on the day of surgery prior to TSE. During the TSE breast adipose tissue from the surgical sample will be snap frozen and stored at -800C for measurement of TAM metabolites. The paraffin block of the DCNB and TSE samples will be acquired by the recruiting institution and 10 sections from each specimen submitted to the NU Pathology Core Facility (NU PCF). The sections will be cut in batches (with pre- and post-samples in the same batch), shipped cold, and processed for immunohistochemistry within a week of sectioning.