BACKGROUND: The Oncotype DX is a quantitative assay of the expression of 16 tumor related genes and 5 reference genes that predicts the potential of adjuvant chemotherapy benefit in estrogen receptor ER positive early breast cancer patients. ...CONCLUSION: Oncotype DX testing resulted in significant changes in the adjuvant treatment decisions in ER positive, HER2 negative early breast cancer particularly in the case of young, luminal B, N1, and stage II IIIA disease....