Endocrine therapy in premenopausal women with breast cancer: a critical appraisal of current evidence.

Nearly 60% of all breast cancer premenopausal women are diagnosed with a hormone receptor positive tumor and, therefore, are candidates for adjuvant hormonal therapy. Treatment with tamoxifen for at least 5 years has been for a long time the standard of care, as it is associated with overall positive clinical outcomes. However, in the last decade, a number of studies on adjuvant endocrine therapy in premenopausal women with hormone receptor positive breast cancer have been published, adding a bulk of evidence to existing knowledge in this field. A critical appraisal of their results appears necessary in order to put the recently collected data into the current framework of treatment, and to discuss the several issues that remain open. Here, we review the most recent evidence on the following: the optimal duration of tamoxifen treatment, results of the studies comparing tamoxifen alone to tamoxifen plus ovarian function suppression (OFS), results of the studies comparing tamoxifen plus OFS to aromatase inhibitors plus OFS.