The Oncotype DX Recurrence Score's Impact on the Management of Oestrogen-Positive/Human Epidermal Growth Factor Receptor 2-Negative, Low-Burden Axillary Status Breast Cancer (REHAB Study): Results of a Single Centre.

Background The Oncotype DX Recurrence Score (ODX-RS) is increasingly utilized in oestrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative, low-burden axillary disease early operable breast cancer. It has been demonstrated to predict the benefits of adjuvant chemotherapy, hence supporting individualized decisions on adjuvant therapy. Aim To investigate the application of ODX-RS as an adjuvant treatment decision tool in breast cancer operated in our unit. Methods A total of 107 eligible patients who were operated on between 2017 and 2021 in Basildon University Hospital, UK were enrolled in this study. In this retrospective study, the clinical data, including patient's age, tumour size, ER status, HER2 status, Ki67 proliferative index (Ki67-PI), nodal status, tumour grade, and ODX-RS, were collected. In the study design, the oncologist had the opportunity to assess the need for adjuvant chemotherapy for patients with ER-positive, HER2-negative, low-burden axillary lymph node disease, early breast cancer by using tumour characteristics and the PREDICT tool without knowing the ODX-RS results. The clinician's decision was matched against the breast multidisciplinary team's recommendations after ODX-RS utilisation, and the results were explored. Results The median ODX-RS of cohort tumours was 18 in the age group > 50 years, with ODX-RS ≥ 26 found in 18% of the group (n = 12). In the age group ≤ 50 years, 17% (n = 7) had ODX-RS between 21 and 25 and only 7% (n = 3) had ODX-RS ≥ 26. Without using ODX-RS, only 16% of the patients had been offered adjuvant chemotherapy in addition to the hormonal manipulation therapy; however, after using ODX-RS, up to 33% of the cohort was suitable for adjuvant chemotherapy in addition to the hormonal manipulation therapy. The changes in the recommendations after ODX-RS utilisation have been noticed in 29% of the cohort. Conclusion This study revealed that ODX-RS supported decision-making regarding postoperative adjuvant chemotherapy, especially when other tumour biomarkers, such as tumour size, grading, or Ki-67, indicated lower risk criteria. Patients with a high ODX-RS were offered chemotherapy where appropriate and its use led to a 15% rate of initial decision change in adjuvant treatment decisions; this involved either recommending chemotherapy or its omission.