The Oncotype DX® test (Genomic Health, Inc., Redwood City CA, USA) is a multigene assay which has been prospectively validated in women with ER-positive, HER2-negative breast cancer in the TAILORx (node negative) and RxPONDER (1–3 lymph nodes positive) trials [13, 14]. The gene discussed is ERBB2; the disease is breast cancer.