Guidance for Canadian Breast Cancer Practice: National Consensus Recommendations for the Systemic Treatment of Patients with HER2+ Breast Cancer in Both the Early and Metastatic Settings (2025 Update)

Area of Science:

• Oncology
• Clinical Practice Guidelines
• Translational Research

Background:

• Human epidermal growth factor receptor 2-positive (HER2+) breast cancer is aggressive with poor prognosis if untreated.
• Recent clinical trials (e.g., DESTINY-Breast05, -09, -11, PATINA, APHINITY) have significantly altered the treatment landscape for HER2+ breast cancer.
• The optimal use of antibody-drug conjugates and systemic therapy sequencing requires updated guidance.

Purpose of the Study:

• To update evidence-informed consensus recommendations for HER2+ breast cancer treatment in Canada.
• To provide guidance on the optimal sequencing of systemic therapies and the role of antibody-drug conjugates.
• To support consistent, high-quality care for HER2+ breast cancer patients.

Main Methods:

• Modified Delphi process with up to three rounds of anonymous voting.
• Consensus defined as ≥75% agreement among clinical-academic oncologists.
• Incorporation of new data for early-stage, metastatic, and CNS-involved disease.

Main Results:

• Revised neoadjuvant and adjuvant treatment pathways for HER2+ breast cancer.
• Expanded guidance on the clinical application of antibody-drug conjugates.
• Updated recommendations reflecting the latest advancements in systemic therapies.

Conclusions:

• The 2025 update provides crucial guidance for managing HER2+ breast cancer in Canada.
• New recommendations address evolving treatment paradigms, including antibody-drug conjugates.
• These guidelines aim to optimize patient outcomes through evidence-based care strategies.