The Modern Landscape of Endocrine Therapy for Premenopausal Women with Breast Cancer

The optimal endocrine therapy for premenopausal women with early and advanced breast cancer still remains an important and controversial issue. For over 30 years, tamoxifen has been the gold standard in the adjuvant setting. New therapeutic options, such as the addition of ovarian function suppression to oral endocrine therapy (either tamoxifen or aromatase inhibitors), can improve outcomes over tamoxifen alone in well-selected patients. Treatment duration has also been revisited, and extended therapy is becoming a new standard of care, especially in high-risk patients. Endocrine therapy for advanced disease still represents a challenge and a research priority. New drugs and combinations able to overcome endocrine resistance are at the horizon, and their role in premenopausal women should be better elucidated. Side effects and quality of life (including family planning considerations) play an important role in treatment selection and in the patients' treatment adherence and should always be discussed before start of treatment. The paper will specifically focus on how to integrate all new treatment options in the current armamentarium of endocrine therapy of premenopausal women, with the aim of best fine-tuning treatment selections according to the individual risk/benefit evaluation.