Only the Oncotype DX Breast Recurrence Score test is clinically validated for prediction of chemotherapy benefit2,5
The Recurrence Score® result has been proven to be predictive of chemotherapy benefit for HR+, HER2-, node-positive postmenopausal patients in the retrospective SWOG-8814 study.1 The prospective randomised trial RxPONDER including more than 5,000 patients was designed to refine chemotherapy benefit estimates for HR+, HER2- patients with Recurrence Score results 0-25 and 1 to 3 positive nodes.3 Initial results of the RxPONDER study have been described as practice-changing.2
RxPONDER study design: node-positive (1-3 nodes) patients with Recurrence Score results 0–25 were randomised to endocrine therapy alone or chemoendocrine therapy3
At a prespecified interim analysis in September 2020, the Data Safety Monitoring Committee advised the study investigators to report the available findings of the clinical trial. Preliminary results were presented at the San Antonio Breast Cancer Symposium on 10 December 20203. A total of 5,015 patients were included in the analysis with a 5.1-year median follow up.
Based on this interim analysis, the authors concluded that the majority of N1 postmenopausal patients do not benefit from adjuvant chemotherapy, independent of clinical pathological parameters and thus can likely forgo adjuvant chemotherapy without compromising IDFS based on Recurrence Score® results 0-25.3
N1 postmenopausal patients with RS® results 0-25 did not benefit from the addition of chemotherapy to endocrine therapy on any endpoint reported4
Based on this interim analysis, the authors suggested that premenopausal patients with N1 breast cancer and Recurrence Score results 0-25 have a modest benefit from adjuvant chemotherapy.2,4
N1 premenopausal patients with RS® results 0-25 have a modest benefit from the addition of chemotherapy with a 2.4% benefit in terms of 5-year distant recurrence-free interval2,4
Prospectively planned analysis in TAILORx established that clinical pathological features and clinical risk, as assessed by tumour size and grade according to modified Adjuvant!Online, add prognostic value to estimate the clinical outcome of patients receiving endocrine therapy alone; however, clinical risk was not associated with response to chemotherapy.3,19
There were further new exploratory analyses aimed at identifying any subgroups of patients who may benefit from chemotherapy. The Recurrence Score result and patient age, in combination, may modify treatment response: patients ≤50 years and with Recurrence Score results 16-25 may benefit from chemotherapy, as detailed in the table below.3,19
