The Warwick Experience of the Oncotype DX® Breast Recurrence Score® Assay as a Predictor of Chemotherapy Administration

Introduction: Oncotype DX® analyses the expression of 21 genes within tumour tissue to determine a Recurrence Score® (RS). RS is a marker of risk for distant recurrence in oestrogen receptor-positive early breast cancer, allowing patient-specific benefit of chemotherapy to be evaluated. Our aim was to determine whether the introduction of Oncotype DX led to a net reduction in chemotherapy use. Methods: Consecutive patients that underwent Oncotype DX at Warwick Hospital were reviewed. Patients were anonymised and re-discussed at a multidisciplinary team meeting (MDM; without RS), and treatment recommendations were recorded. This was compared to the original MDM outcome (recommendations made with RS). Differences were analysed using Wilcoxon signed-rank test. Results: 67 patients were identified. Proportions of high, intermediate and low risk were 28, 33 and 39% (n = 19/22/26), respectively. Without RS, 56 (84%) patients were recommended for chemotherapy and 3 were not. The remaining 8 patients were deemed borderline for requiring chemotherapy and referred for discussion with an oncologist. With availability of RS, 34 (50%) patients were recommended for chemotherapy, and 24 (43%) patients were spared chemotherapy (p < 0.0005). The net reduction in chemotherapy was 33%. Conclusion: There has been a significant reduction in chemotherapy usage in patients at Warwick since the introduction of Oncotype DX.