Hormonal therapy for primary breast cancer: scientific rationale and status of clinical research.

Endocrine therapies have played an important role in the management of breast cancer for many years. Tamoxifen had been the unchallenged standard in the adjuvant setting until recently. Data from recent clinical trials have emphasized the emerging roles of aromatase inhibitors and ovarian ablation in patients with early breast cancer. This review highlights previous data that led to the recognition of tamoxifen as the gold standard hormonal therapy in the adjuvant treatment of early breast cancer. We then discuss clinical trials demonstrating the impact of aromatase inhibitors as an alternative to tamoxifen or as a component of sequential treatment with tamoxifen in postmenopausal women with early breast cancer. Finally, we review data related to the incorporation of ovarian ablation into the treatment of early breast cancer in premenopausal women.