• Systematic literature review of 56 studies assessing clinical and economic implications of risk stratifiers for ESBC.
• The 21-gene Recurrence Score^® met highest level of evidence for estimating recurrence risk, OS and response to adjuvant chemotherapy.

Like many similar efforts, this initiative compared available clinical trial evidence supporting the use of several commonly used prognostic/predictive assays in the adjuvant breast cancer setting. Using rigorously defined criteria based on levels of evidence, the authors of this study, like others before them, concluded that the data with Oncotype DX^® were more robust than those with other available assays, including the 70-gene signature, 5-antibody IHC panel and Adjuvant! Online. This finding seems to have already been appreciated as ASCO, NCCN, St Gallen and oncologists in practice currently position the Oncotype DX assay more favorably than others. At another level it is worth considering the challenge involved both for the public and private sectors to develop the necessary research foundation for a predictive/prognostic assay. For Oncotype DX, this involved complex, resource-demanding studies with cooperative groups like the NSABP followed by more work evaluating the assay in clinical practice, assessing both the clinical and financial consequences. This is a high bar with considerable development costs that poses a hurdle to entities wishing to move the field forward.