Escalation and De-Escalation Strategies for Endocrine Therapy in Early-Stage Breast Cancer.

Although adjuvant endocrine therapy (ET) greatly lowers the risk of recurrence and mortality in hormone receptor (HR)-positive early-stage breast cancer (EBC), more than 20% of patients may experience relapses within 10 years, often manifesting as incurable distant metastases. To improve outcomes, ovarian function suppression (OFS) with gonadotropin-releasing hormone agonists (GnRHa) added to tamoxifen or aromatase inhibitors like exemestane have shown significant disease-free survival (DFS) and, in some cases, overall survival (OS) benefits. CDK4/6 inhibitors, a cornerstone in metastatic HR-positive, HER2-negative breast cancer (MBC), are now being explored in EBC. Trials with abemaciclib and ribociclib have shown promise in high-risk EBC. For BRCA-mutant patients, the PARP inhibitor olaparib, as demonstrated in the OlympiA trial, significantly improved invasive DFS and OS when used as adjuvant therapy for one year. Conversely, de-escalation strategies are also emerging. Recent studies suggest that younger premenopausal women with low-risk disease may safely interrupt ET after 18-30 months to pursue pregnancy. Additionally, genomic tumor profiling is widely utilized to decide on aggressiveness of adjuvant therapy of EBC. These advancements reflect a shift toward personalized adjuvant therapy, integrating targeted treatments like CDK4/6 inhibitors and PARP inhibitors, optimizing ET with OFS, and balancing efficacy with quality of life through de-escalation strategies. This tailored approach aims to improve long-term outcomes for HR-positive EBC patients.