Abstract
Therapies targeting human epidermal growth factor receptor 2 (HER2)-positive breast cancer significantly impact patient outcomes, quality of life, and health care systems. While chemotherapy and trastuzumab improve survival in early-stage HER2-positive breast cancer, variability in clinical and biological characteristics leads to different response to therapies and outcomes. Clinical guidelines provide general recommendations, but significant uncertainty persists in identifying an optimal treatment plan for individual patients. The HER2DX genomic test informs treatment decisions for stage 1-3 HER2-positive breast cancer by integrating biological factors and clinical factors (tumor size and nodal status). It provides three scores relevant to patient management: long-term prognosis (risk score), likelihood of achieving pathological complete response (pCR score), and ERBB2 mRNA expression (ERBB2 score). This article offers an expert overview of HER2DX, covering score interpretation, clinical applications, ongoing studies, and future directions. By analyzing the genomic profiles of HER2-positive tumors, HER2DX provides independent information regarding therapeutic responses and disease prognosis, thereby enabling physicians to navigate the increasing complexity of managing patients with HER2-positive early breast cancer. Key findings show that HER2DX predicts relapse-free survival and probability of pCR to a variety of neoadjuvant therapy regimens, which aids in personalizing treatment plans that could reduce over-treatment and under-treatment. The article underscores expert recommendations to help integrate HER2DX into clinical practice, aiming to enhance decision making and clinical outcomes.