ERBB2 and breast cancer: Oncotype DX (Genomic Health, Redwood City, CA; hereafter referred to as ODX) is a genetic test that calculates a recurrence score (RS) on the basis of the RNA expression levels of 21 genes in tumor tissue from patients with invasive BC, including 16 tumor‐related genes and five reference genes, and is one of the most commonly used genetic diagnostic technologies in the clinic to predict the outcome and response to chemotherapy of hormone receptor (HR)‐positive and human epidermal growth factor receptor 2 (HER2)‐negative BC [16, 17, 18].