Initial Treatment Strategy for Newly Diagnosed HER2 Positive Metastatic Breast Cancer With Visceral Disease

This segment introduces a patient with newly diagnosed HER2 positive metastatic breast cancer presenting with pulmonary and hepatic involvement after prior adjuvant therapy. The discussion focuses on clinical assessment, confirmation of metastatic disease, and how prior treatment history, disease-free interval, visceral burden, and performance status inform first-line systemic therapy selection. Panelists emphasize that despite hormone receptor positivity, the presence of multifocal liver and lung metastases favors early use of HER2 directed therapy rather than endocrine-based approaches alone. DESTINY-Breast09 data are discussed as a potential option in this setting, particularly given the absence of prior pertuzumab exposure. The discussion highlights how real-world decision making balances historical standards, emerging ADC data, and patient-specific factors to prioritize therapies with the greatest likelihood of rapid and durable disease control.