ABSTRACT
PURPOSE: The treatment landscape of Oestrogen receptor-positive (ER-positive) breast cancer is evolving, with declining chemotherapy use as a result of Oncotype DX Breast Recurrence Score® testing. Results from the SWOG S1007 RxPONDER trial suggest that adjuvant chemotherapy may benefit some premenopausal women with ER-positive, HER2-negative disease with 1-3 positive lymph nodes (N1), and a Recurrence Score® (RS) of ≤ 25. Postmenopausal women with similar characteristics did not benefit from adjuvant chemotherapy. We examine the clinical and economic impact of Oncotype DX® testing on treatment decisions in patients with N1 disease in Ireland using real world data. METHODS: From March 2011 to October 2022, a retrospective, cross-sectional observational study was performed of patients with ER-positive, HER2-negative N1 breast cancer, who had Oncotype DX testing across 5 of Ireland's largest cancer centres. Patients were classified into low risk (RS 0-13), intermediate risk (RS 14-25) and high risk (RS > 25). Data were collected via electronic patient records. Information regarding costing was provided primarily by pre-published sources. RESULTS: A total of 828 N1 patients were included in this study. Post Oncotype DX testing, 480 patients (58%) were spared chemotherapy. Of the patients who had a change in chemotherapy recommendation based on Oncotype DX testing, 271 (56%), 205 (43%), 4 (1%) had a RS result of 0-13, 14-25 and > 25 respectively. Use of Oncotype DX testing was associated with a 58% reduction in chemotherapy administration overall. This resulted in estimated savings of over 6 million in treatment costs. Deducting the assay cost, estimated net savings of over 3.3 million were achieved. Changes in the ordering demographics of Oncotype DX tests were identified after RxPONDER data were presented, with increased testing in women ≥ 50 years and a reduction in proportion of tests ordered for women < 50 years. CONCLUSION: Between 2011 and 2022, assay use resulted in a 58% reduction in chemotherapy administration and net savings of over 3.3 million.