The Oncotype DX assay (Genomic Health), a commercially available 21-gene breast cancer recurrence score (RS) assay, is one of several gene-expression assays that are used to predict prognosis in hormone receptor-positive breast cancer [1]. The Oncotype DX assay provides RS values ranging from 0 to 100, with higher scores indicating a worse prognosis and a greater likelihood of benefiting from chemotherapy [2]. A high RS, defined as 31 or higher (or 26 or higher in some cases), suggests a potenti…