Ovarian Function Suppression in Premenopausal Women with Concurrent Endocrine Therapy Use

Revisiting ovarian function suppression with GnRH agonists for premenopausal women with breast cancer: Who should use and the impact on survival outcomes

Breast cancer diagnosed in premenopausal women tends to be more aggressive and the benefit of ovarian function suppression (OFS), at least in certain groups of patients, is well known. There is hesitancy in using OFS in some groups of patients who may otherwise benefit from the treatment. For instance, it is clear that in premenopausal patients with hormone receptor-positive (HR+), high-risk, early-stage breast cancer, gonadotropin-releasing hormone agonists (GnRHa) should be given in the adjuvant setting; however, confusion remains whether premenopausal patients with intermediate-risk disease benefit from GnRHa, given the lack of consensus on its definition in guidelines and clinical practice. Most recent evidence on the long-term efficacy of GnRHa, with up to 20-years of follow-up, reinforced its benefits in premenopausal patients with early-stage breast cancer. In this comprehensive review, we reviewed the long-term efficacy in terms of improvement in disease-free survival (DFS) and overall survival (OS) for early-stage HR+ breast cancer and examined evidence from multiple randomized clinical studies to identify the clinicopathological characteristics that correlated with improved DFS and OS with the addition of OFS to adjuvant endocrine therapy. Other aspects of GnRHa, including its efficacy in advanced breast cancer, safety profile, evidence in ovarian function preservation, and the advantages of long-acting formulations were also discussed. By addressing the existing gaps and grey areas regarding the inclusion of OFS as a crucial treatment component for premenopausal breast cancer patients, physicians are more aware of who to administer and the potential impact on survival outcomes.

Selection of appropriate biomarkers to monitor effectiveness of ovarian function suppression in pre-menopausal patients with ER+ breast cancer

Use of gonadotropin-releasing hormone (GnRH) agonists has been widely adopted to provide reversible ovarian function suppression for pre-menopausal breast cancer patients who are also receiving aromatase inhibitor or tamoxifen therapy based on results of 25 randomized trials representing almost 15,000 women demonstrating a survival benefit with this approach. Past clinical trials designed to establish the efficacy of GnRH agonists have monitored testosterone in the prostate cancer setting and estradiol in the breast cancer setting. We explore the merits of various biomarkers including estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) and their utility for informing GnRH agonist treatment decisions in breast cancer. Estradiol remains our biomarker of choice in ensuring adequate ovarian function suppression with GnRH agonist therapy among pre-menopausal women with breast cancer. We recommend future trials to continue to focus on estradiol levels as the primary endpoint, as they have in the past.