<qa>  What is the effect of Tamoxifen on the incidence of contralateral breast cancer?Tamoxifen has been shown to reduce the incidence of contralateral breast cancer regardless of the estrogen expression of the primary tumor and may therefore be offered as a chemopreventive agent to patients who have not received an anti-estrogen in the adjuvant setting. This population of patients is also a reasonable cohort in which to test other chemoprevention regimens. Our hypothesis is that the combination of raloxifene and exemestane may offer an alternative treatment for chemoprevention that may prove to be more effective than an anti-estrogen alone. 