Human epidermal growth factor receptor 2-positive (HER2+) breast cancer is an aggressive subtype of breast cancer associated with a poor prognosis when sub-optimally treated. Recent advances include new and effective targeted therapies that have significantly improved outcomes for patients. Despite these advances, there are significant gaps across Canada, underscoring the need for evidence-based consensus guidance to inform treatment decisions. Addressing these gaps is crucial to ensuring that effective therapies are integrated into clinical practice, so as to improve the lives of patients affected by this aggressive form of breast cancer. The Research Excellence, Active Leadership (REAL) Canadian Breast Cancer Alliance is a standing nucleus committee of clinical-academic oncologists across Canada and Breast Cancer Canada, a patient organization. The mandate of this group is to provide evidence-based guidance on best practices in the management of patients with breast cancer. These consensus recommendations were developed using a modified Delphi process with up to three rounds of anonymous voting. Consensus was defined a priori as ≥75% of voters agreeing with the recommendation as written. There are 9 recommendations in the early setting; 7 recommendations in the metastatic setting; and 10 recommendations for patients with brain metastases.

Cyclin-dependent kinase (CDK)4/6 inhibitors have become a key component of adjuvant treatment for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2−) early breast cancer who are at high risk of recurrence. The addition of abemaciclib and ribociclib to standard endocrine therapy has demonstrated clinically meaningful improvements in invasive disease-free survival, supported by the monarchE and NATALEE trials, respectively. With expansion of patient eligibility for CDK4/6 inhibitors, multidisciplinary coordination among medical oncologists, surgeons, nurses, pharmacists, and other health care providers is critical to optimizing patient identification, monitoring, and management of adverse events. This expert guidance document provides practical recommendations for implementing adjuvant CDK4/6 inhibitor therapy in routine clinical practice, incorporating insights from multiple specialties and with patient advocacy representation. Key considerations include patient selection based on clinical trial data, treatment duration, dosing schedules, adverse event profiles, monitoring requirements, drug–drug interactions, and patient-specific factors such as tolerability, cost, and quality of life. This guidance aims to support Canadian clinicians in effectively integrating CDK4/6 inhibitors into clinical practice, ensuring optimal patient outcomes through a multidisciplinary and patient-centric approach.

The use of systemic therapy before surgery (“neoadjuvant therapy”) is the standard of care for the treatment of locally advanced and nonoperable breast cancer. The advantages of neoadjuvant therapy include improved rates of breast-conserving surgery, the possibility of early measurement of response, and potentially improved outcomes for certain subgroups of high-risk patients. The use of neoadjuvant therapy in operable breast cancer is increasing, although there are no clear guidelines in Canada to help guide patient selection and management. Multidisciplinary experts in the diagnosis and treatment of locally advanced breast cancer (labc) converged at the fourth annual meeting of the Canadian Consortium for LABC (colab) to further their goals of improved standards for neoadjuvant care and clinical research through education and collaboration. Canadian clinical researchers were joined by Dr. Michael Untch of the Helios Hospital Berlin–Buch—representing the German neoadjuvant treatment groups German Gynecologic Oncology Working Group (Arbeitsgemeinschaft Gynakologische Onkologie) and German Breast Group—to discuss the advancement of research in the neoadjuvant setting and important issues of clinical care and investigator-led research. The group reached a consensus on the importance of multidisciplinary collaboration, the use of clips to mark tumour location, and core biopsy testing for the estrogen and progesterone receptors and the human epidermal growth factor receptor 2 at the time of diagnosis. Other initiatives—including creation of a prospective database, inception of the colab Neoadjuvant Network, and development of a clinical survey to evaluate current practice—continue to further the colab mandate of transforming the neoadjuvant treatment landscape in Canada.