The genomic tests such as the 70-gene expression assays (MammaPrint) and 21-gene expression assays (Oncotype DX) may be used to inform decisions on withholding adjuvant chemotherapy in HR+/HER2- breast cancer patients with high clinical risk due to their ability to identify populations with a good prognosis and potentially limited chemotherapy benefit (6). This evidence concerns the gene ERBB2 and breast cancer.