Adjuvant endocrine therapy of premenopausal women with early breast cancer: an overview

Abstract

Tamoxifen is currently the standard of care for premenopausal women with hormone receptor-positive early breast cancers. However, endocrine strategies in premenopausal women include not only estrogen receptor blockade with tamoxifen but also temporary suppression of ovarian estrogen synthesis by luteinizing hormone-releasing hormone (LHRH) agonists, or permanent interruption of ovarian estrogen synthesis with oophorectomy or radiotherapy. Luteinizing hormone-releasing hormone agonists have proven to be as effective as surgical oophorectomy in adjuvant treatment of premenopausal breast cancer. The addition of LHRH agonists compared to no therapy reduces the annual odds of recurrence and death in premenopausal women aged less than 50 years with estrogen receptor-positive tumors. Luteinizing hormone-releasing hormone agonists alone or in combination with tamoxifen have shown disease-free survival rates similar to chemotherapy with CMF (cyclophosphamide/methotrexate/5-fluorouracil) and other second-generation chemotherapies. The role of aromatase inhibitors in combination with ovarian suppression is still not established, especially as a large phase III randomized study (Austrian Breast and Colorectal Cancer Study Group Trial 12) did not show superior efficacy compared with ovarian suppression plus tamoxifen in premenopausal early stage disease. Patients currently continue to receive ovarian suppression and tamoxifen. CYP2D6 status may become an important discriminator for the type of endocrine therapy for the premenopausal patient in the future.