New Canadian recommendations for treatment of HER2+ breast cancer

New Canadian evidence-based guidance is now available on the best practices for management of human epidermal growth factor receptor 2-positive (HER2+) breast cancer. The guidance document was prepared by the Research Excellence, Active Leadership (REAL) Canadian Breast Cancer Alliance, a standing committee of clinical–academic oncologists across Canada, and Breast Cancer Canada, a patient organization.HER2+ breast cancer accounts for approximately 14% of breast cancer cases in Canada. It is an aggressive subtype of breast cancer associated with a poor prognosis when treated suboptimally. Recent advances, including new and effective targeted therapies, have significantly improved outcomes for patients. However, despite these advances, significant care gaps exist across Canada, highlighting the need for evidence-based consensus guidance to inform treatment decisions. The new evidence-based best practices aim to address these gaps and ensure that effective therapies are integrated into clinical practice. The goal is to improve overall care delivery to all patients affected by this aggressive form of breast cancer. The consensus recommendations were developed using a modified Delphi process with up to three rounds of anonymous voting. Consensus was defined as ≥ 75% of voters agreeing with the recommendation. The guidance document includes nine recommendations for treatment of HER2+ breast cancer in the early setting, seven recommendations in the metastatic setting, and 10 recommendations for patients with brain metastases.Systemic therapy in HER2+ early breast cancer: summary of recommendations For patients with HER2+ early breast cancer cT1a and b (i.e., ≤ 1 cm) without evidence of nodal disease (cN0), the standard of care is timely surgery followed by adjuvant treatment depending on the pathologic staging of disease (strong recommendation).For patients with HER2+ early breast cancer cT1c (i.e., >1 to ≤ 2 cm) without evidence of nodal disease (cN0), the standard of care is surgery followed by adjuvant treatment (strong recommendation). However, due to current global practices, consideration can be given to neoadjuvant treatment followed by surgery and adjuvant treatment (strong consideration).For patients with HER2+ early breast cancer with pT1 without evidence of nodal disease (pN0), the standard of care adjuvant systemic treatment is paclitaxel plus trastuzumab for 12 weeks followed by trastuzumab monotherapy for nine months (strong recommendation).Although neoadjuvant treatment is preferred, for those patients who are treated with upfront surgery and are then found to have ≥ pT2 pN0 disease, the standard of care is adjuvant chemotherapy plus trastuzumab (strong recommendation).For patients with HER2+ early breast cancer with ≥ cT2 or those with nodal disease (cN+), the standard of care is neoadjuvant therapy with trastuzumab plus pertuzumab plus chemotherapy (strong recommendation).Although neoadjuvant treatment is preferred, for those patients who are treated with upfront surgery and are then found to have nodal disease in the pathological specimen (pN+), the standard of care is adjuvant chemotherapy plus trastuzumab with consideration given to the addition of pertuzumab (strong consideration).For patients with HER2+ early breast cancer in whom a pathologic complete response is determined in the surgical specimen after completion of neoadjuvant trastuzumab plus pertuzumab plus chemotherapy, the standard of care is trastuzumab for a total of one year (strong recommendation).For patients with HER2+ early breast cancer in whom residual invasive disease is detected pathologically in the surgical specimen of the breast or axillary lymph nodes after completion of neoadjuvant trastuzumab plus pertuzumab plus chemotherapy, the standard of care is to treat with trastuzumab emtansine (T-DM1) for 14 cycles in the adjuvant setting (strong recommendation).Although there is not a survival benefit, for patients with HER2+ HR+ and N+ disease who have completed (neo)adjuvant chemotherapy plus trastuzumab, extended adjuvant treatment with neratinib for one year after completion of trastuzumab-based adjuvant therapy can be considered to decrease recurrence (moderate recommendation).Detailed discussion of each of these recommendations is provided in the guidance document. The document also outlines recommendations for management of HER2+ metastatic breast cancer, and recommendations for managing patients with brain metastases.The authors note that these recommendations will be updated as new data become available. They also comment that these REAL Alliance recommendations align with all other international guidelines, with the exception that the REAL Alliance recommends screening patients for asymptomatic brain metastases at the time of diagnosis with stage 4 HER2+ disease. The authors stress that the goal of the REAL Alliance is to promote best practices, as well as timely and equitable access to treatments and care for patients with HER2+ breast cancer across Canada.Reference:Manna M, Gelmon KA, Boileau JF, et al. 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 setting. Curr Oncol 2024;31:6536-67. (accessed December 3, 2024).

New Canadian recommendations for treatment of HER2+ breast cancer

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