Expert consensus on the clinical diagnosis and targeted therapy of HER2 breast cancer (2023 edition)

Area of Science:

• Oncology
• Molecular Diagnostics
• Pharmacology

Background:

• Human epidermal growth factor receptor 2 (HER2) is a critical biomarker in breast cancer, influencing prognosis and response to targeted therapies.
• Advancements in anti-HER2 drugs have significantly improved outcomes for HER2-positive breast cancer patients.
• The definition of HER2-low expression (IHC 1+ or IHC 2+ and ISH-negative) is crucial for treatment decisions.

Purpose of the Study:

• To update expert consensus recommendations for optimizing the treatment of HER2-positive and HER2-low breast cancer.
• To incorporate new evidence on antibody-drug conjugates (ADCs) like trastuzumab deruxtecan (T-DXd).
• To provide guidance on whole-course management, including during the COVID-19 pandemic.

Main Methods:

• Review and synthesis of current clinical research and real-world evidence on HER2-targeted therapies.
• Development of updated recommendations for different stages of breast cancer, from early to metastatic.
• Inclusion of specific guidance for HER2-low breast cancer based on updated definitions.

Main Results:

• New treatment recommendations for HER2-positive breast cancer, adjusting levels from early to metastatic stages.
• Introduction of a dedicated chapter for HER2-low breast cancer, recommending appropriate regimens.
• Emphasis on the efficacy of ADCs in both HER2-positive and HER2-low breast cancer.

Conclusions:

• Updated consensus optimizes HER2 breast cancer management by integrating novel therapies and defining HER2-low status.
• Recommendations support personalized treatment strategies, considering disease stage and HER2 expression levels.
• Focus on low-toxicity regimens and oral preparations is advised for comprehensive patient care.