Precision oncology in breast cancer: Biomarker-driven treatment strategies and the expanding role of APPs.

Abstract

Abstract: Recent advances in breast cancer management have transformed treatment across molecular subtypes and expanded the role of precision oncology. Hormone receptor-positive (HR-positive), human epidermal growth factor receptor 2-positive (HER2-positive), HER2-low, and triple-negative breast cancer (TNBC) each demonstrate distinct biologic behavior requiring tailored therapeutic strategies. In HR-positive disease, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and next-generation selective estrogen receptor degraders have improved survival, while HER2-directed antibody-drug conjugates (ADCs) have expanded treatment options beyond traditional HER2-positive disease. HER2-low disease has recently emerged as a therapeutically actionable HER2-expression category, addressing a previously limited treatment space. In TNBC, immunotherapy and ADCs have broadened therapeutic options for historically difficult-to-treat disease. Advances in genomic profiling, including next-generation sequencing and circulating tumor DNA testing, allow clinicians to identify biomarkers to guide targeted therapy selection. As treatment complexity increases, APPs play an essential role in implementing precision oncology through patient education, toxicity management, genomic counseling, and clinical trial coordination. This review summarizes current treatment strategies across breast cancer subtypes, highlights emerging therapies, and emphasizes the expanding APP role.