Advances in Systemic Treatment of Breast Cancer.

A New England Journal of Medicine review traces systemic therapy for breast cancer since 2020, covering targeted therapies, antibody-drug conjugates and immunotherapy across biologic subtypes. CDK4/6 inhibitors remain foundational in hormone-receptor-positive, HER2-negative disease, trastuzumab deruxtecan is reshaping HER2-positive treatment, and immune checkpoint inhibitors have improved outcomes in triple-negative breast cancer. Unresolved issues include treatment sequencing, predictive biomarkers, circulating tumor DNA analysis and equitable access to high-cost therapies.