Neoadjuvant Endocrine Therapy in Breast Cancer Management: State of the Art

SIMPLE SUMMARY: Over the last ten years, neoadjuvant endocrine therapy (NET) has been increasingly investigated and has gained recognition. NET should not only be used to allow surgery or to improve breast-conserving surgery rates in patients not eligible for NCT, but also as a research tool for the search for endocrine sensitivity biomarkers and targeted therapies, and for prognostic information in ER+/HER2-. ABSTRACT: Endocrine therapy is the mainstay of treatment in HR+/HER2- breast cancers, which represent about 70% of all breast cancers. Neoadjuvant therapy has been developed since the 1990s to address several issues, including breast-conserving surgery (BCS) and improvement of survival rates. For a long time, neoadjuvant endocrine therapy (NET) was confined to frail patients in order to improve surgery outcome. Since the 2000s, NET now plays a central role as a research tool for predictive endocrine sensitivity biomarkers and targeted therapies. One of the major issues in early HR+/HER2- breast cancer is to identify patients in whom chemotherapy can be safely withheld. In vivo assessment of response to NET might be the best treatment strategy to address this issue.