A prospective clinical utility study of the impact of the 21-gene recurrence score assay (Oncotype DX) in estrogen receptor positive (ER+) node negative (pN0) breast cancer in academic Canadian centers.

Abstract

549^ Background: The Oncotype DX 21-gene Recurrence Score assay (RS) can potentially predict the magnitude of chemotherapy benefit in patients with stage I-II, node-negative, ER+ disease who will be treated with tamoxifen for 5 years. While use in the United States has grown significantly since its introduction, it is not yet routinely ordered by oncologists in most parts of Canada. The primary purpose of this study was to measure the impact of the Oncotype DX test on the physician’s treatment recommendation in ER+ pN0 breast cancer in British Columbia. Methods: After providing informed consent, patients and medical oncologists completed respective pre-RS questionnaires indicating their treatment preferences and level of confidence and a decisional conflict scale (patients only). At a subsequent visit, after the RS result was known and discussed, the patient and oncologist completed a second set of questionnaires. The proportion of physician treatment recommendations that changed from baseline to follow-up (post RS) were calculated with 95% confidence interval (CI). A prospective health economic (HE) analysis was also performed. Results: From May 2010 to July 2011, two participating BCCA centres enrolled 156 patients. Of the 150 for whom successful RS assay results were obtained, physicians changed their chemotherapy recommendation in 45 cases (30%; 95% CI 22.8-38.0%); either to add (10%; 95% CI 5.7-16.0%) or omit (20%; 95% CI 13.9-27.3%) adjuvant chemotherapy. As a secondary end-point, in 84 cases (56%; 95% CI 47.7-64.1%) there was a change in either the planned chemo and/or endocrine therapy recommendation. There was an overall significant improvement in physician confidence post RS (p < 0.001). Patient decisional conflict also significantly decreased following the RS assay (p < 0.001). The HE analysis is ongoing and will be presented separately. Conclusions: Within the context of a publicly funded health care system, the RS assay significantly affects adjuvant treatment recommendations in ER+ node negative breast cancer, in addition to reducing patient decisional conflict.