Guidance for Canadian Breast Cancer Practice: National Consensus Recommendations for the Systemic Treatment of Patients with HR+/HER2− Metastatic Breast Cancer 2025

Hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer accounts for approximately two-thirds of all breast cancers. The treatment landscape for HR+/HER2- metastatic breast cancer has evolved in recent years, with multiple new therapies demonstrating clinical efficacy and improved patient outcomes. To provide evidence-informed guidance on best practices in the management of patients with HR+/HER2- metastatic breast cancer in Canada, consensus recommendations were developed by Research Excellence, Active Leadership Canadian Breast Cancer Alliance (REAL Alliance), a standing nucleus committee with both clinical-academic oncologists from across Canada and representatives from Breast Cancer Canada, a patient advocacy organization. Recommendations were generated using a modified Delphi approach involving up to three anonymous voting rounds, with a predefined consensus threshold of 75%. These consensus recommendations offer guidance on optimal therapeutic strategies for HR+/HER2- metastatic breast cancer within the Canadian landscape, including integration of precision oncology and targeted therapies, optimal sequencing of therapies, and the importance of balancing the benefits of treatments with patient quality of life and preferences.