Current controversies in the use of Oncotype DX in early breast cancer

Multigene prognostic genomic assays have become essential tools in the management of early breast cancer (BC), providing information that help in risk-stratification, to provide risk-adapted decision-making of adjuvant treatments. Clinical practice guidelines recommend refining the prognostic information provided by clinical and pathology features with the use of genomic tests, such as Oncotype DX®, to classify cancers into risk groups and inform adjuvant treatment strategies. However, the clinical value (i.e., prognostic and/or predictive) and applicability of these assays vary due to differences in the clinical setting, especially in those populations that were underrepresented in pivotal clinical trials. Oncotype DX® is a broadly utilized genomic test for breast cancer, having the highest level of supporting evidence to inform clinical practice. Our manuscript provides a comprehensive overview on this recurrence score assay, evaluates supporting evidence across patient pop- ulations, and discusses their impact on treatment decisions in those groups of patients underrepresented in pivotal clinical trials, where evidence is limited with the use of Oncotype DX.