ESR1 and breast cancer: The PAM50 expression assay with integration of breast cancer subtype and proliferation score in risk assessment was shown to provide better prognostic information in ER-positive, node-negative patients than Oncotype DX.24 Agreement between risk classifications based on Oncotype DX and PAM50 was as low as 54%, demonstrating substantial differences between the molecular classifiers in patient risk stratification.25 However, none of the current multi-gene expression assays have included the very important and prognosis-related immunity genes.