Role of Patient and Disease Factors in Adjuvant Systemic Therapy Decision Making for Early-Stage, Operable Breast Cancer: Update of the ASCO Endorsement of the Cancer Care Ontario Guideline

PURPOSE: To update the American Society of Clinical Oncology endorsement of the Cancer Care Ontario recommendations on the Role of Patient and Disease Factors in Adjuvant Systemic Therapy Decision Making for Early-Stage, Operable Breast Cancer. METHODS: Two phase III trials-the Trial Assigning Individualized Options for Treatment (TAILORx) in women with hormone receptor-positive, node-negative tumors and the Microarray in Node-Negative and 1 to 3 Positive Lymph Node Disease May Avoid Chemotherapy (MINDACT) trial-provided the evidence for this update. UPDATED RECOMMENDATIONS: DX scores of 26 to 30.The MammaPrint assay could be used to guide decisions on withholding adjuvant systemic chemotherapy in patients with hormone receptor-positive lymph node-negative breast cancer and in select patients with lymph node-positive cancers. In both patients with node-positive and node-negative disease, evidence of clinical utility of the MammaPrint assay was only apparent in those determined to be at high clinical risk; the Panel thus did not recommend use of MammaPrint assay in patients determined to be at low clinical risk. Remaining recommendations from the 2016 ASCO guideline endorsement are unchanged.Additional information is available at www.asco.org/breast-cancer-guidelines.