ESR1 and breast cancer: We have demonstrated that the 21-gene assay is a cost-effective tool for determining which ER/PR+, Her2/neu negative early breast cancer patients receive adjuvant chemotherapy when used in two scenarios in the Austrian context; first when used only in patients with a high or intermediate AO risk score (strategy NYY) (ICER 1600 EUR/QALY) and second, when used in all patients independent of the AO risk score (Strategy YYY) (ICER 15,700 EUR/QALY).