Ovarian Function Suppression in Premenopausal HR-positive, HER2-negative Early Breast Cancer: Integrating Clinical Trial Evidence and Findings from a Nationwide Korean Breast Cancer Society Survey

Premenopausal women with hormone receptor–positive breast cancer represent a unique clinical population with distinct endocrine physiology and treatment challenges. Ovarian function suppression (OFS), administered either with tamoxifen (TAM) or aromatase inhibitor, has emerged as a key component in optimizing endocrine therapy. This review integrates current evidence from pivotal clinical trials and incorporates real-world practice patterns from a nationwide survey of members of the Korean Breast Cancer Society (KBCS) to delineate current OFS practice patterns and remaining areas of uncertainty. A national electronic survey was distributed to KBCS members, assessing preferred systemic and endocrine treatment strategies across nine clinical vignettes differing by age, tumor size, nodal status, and genomic risk. The survey findings were contextualized with data from landmark randomized trials and major meta-analyses. Clinical trial evidence supports OFS primarily for high-risk premenopausal women— those who are younger, node-positive, or have high-risk genomic profiles. In contrast, real-world responses demonstrated wider adoption, including frequent use in women <35 years of age with node-negative or genomic lowrisk disease. Lymph-node metastasis was the most powerful driver of OFS recommendations, reaching near-universal use in patients with >5 positive nodes. For extended endocrine therapy (years 6–10), most clinicians preferred TAM alone, regardless of initial risk. Although evidence from randomized clinical trials confirms the efficacy of OFS in selected high-risk patients, its application in daily practice is considerably broader, often encompassing lower-risk populations where benefit remains uncertain. These findings underscore the need for validated predictive biomarkers to identify patients most likely to benefit from OFS while minimizing overtreatment. As precision-guided endocrine therapy continues to evolve, individualized OFS strategies will be essential to balance efficacy, toxicity, and quality of life.