Systemic Therapy for Patients With Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer: ASCO Clinical Practice Guideline Update Summary

The goal of this update is to provide oncologists, other health care practitioners, patients, and caregivers with recommendations regarding optimal management of patients with human epidermal growth factor receptor 2 (HER2)–positive metastatic breast cancer.1 ASCO first published two evidence-based clinical practice guidelines on optimal management of patients with HER2-positive metastatic breast cancer in 2014.2,3 The goal of this 2018 guideline update is to provide oncologists and other clinicians with current recommendations regarding the treatment of patients with HER2-positive metastatic breast cancer. The current 2018 update assesses whether the 2014 recommendations remain valid. No additional evidence was identified that would warrant a change. A complete list of previous recommendations, the updated brain metastases1 and HER2-positive breast cancer guidelines,2 and additional information are available at www.asco.org/breast-cancer-guidelines. Patient information is available at www.cancer.net. THE BOTTOM LINE Systemic Therapy for Patients With Advanced Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer: ASCO Clinical Practice Guideline Update Guideline Question What is the optimal medical therapy for advanced human epidermal growth factor receptor 2 (HER2)–positive breast cancer, specifically HER2-targeted therapy, either alone or in combination with chemotherapy and/or endocrine therapy? Target Population Individuals with advanced HER2-positive breast cancer Target Audience Medical oncologists, radiation oncologists, surgeons, oncology nurses, and patients/caregivers Methods A systematic review of the literature was performed and relevant evidence was evaluated for inclusion into this updated clinical practice guideline using the signals approach. Recommendations Clinicians should recommend HER2-targeted therapy–based combinations for first-line treatment, except for highly selected patients with estrogen receptor–positive or progesterone receptor–positive and HER2-positive disease, for whom clinicians may use endocrine therapy alone (Type: evidence based; Evidence quality: high; Strength of recommendation: strong). If a patient’s HER2-positive advanced breast cancer has progressed during or after first-line HER2-targeted therapy, clinicians should recommend second-line HER2-targeted therapy– based treatment (Type: evidence based; Evidence quality: high; Strength of recommendation: strong). If a patient’s HER2-positive advanced breast cancer has progressed during or after second-line or greater HER2-targeted treatment, clinicians