P4-09-18: Australian Decision Impact Study: The Impact of Oncotype DX Recurrence Score (RS) on Adjuvant Treatment Decisions in Hormone Receptor Positive (HR+), Node Negative (N0) and Node Positive (N+) Early Stage Breast Cancer (ESBC) in the Multidisciplinary Clinic (MDC).

Abstract

Abstract Introduction: There has been increasing interest in more accurately defining the need for chemotherapy in patients with HR+ ESBC. Oncotype DX® has been shown to provide prognostic and predictive information beyond traditional histopathological factors. Prior clinical impact studies have focused on decisions made by individual practitioners. In Australia, the MDC has become the standard forum for determining treatment decisions. In this study, we have assessed how the RS influences adjuvant systemic treatment decisions in the MDC at 4 separate hospitals. Methods: Patients with unifocal HR+, HER2−ve ESBC, N0 and N+ (1-3 positive nodes, including micrometastases and isolated tumour cells) and no contraindication to adjuvant chemotherapy (CTx) or endocrine therapy (H) were eligible. A total of 150 patients will be entered. Systemic adjuvant treatment recommendations were made and recorded in the MDC, both before and after testing with Oncotype DX. The primary endpoint was the overall change in the treatment recommendation. Other endpoints included confidence in recommendations, assessment of impact of the RS, and treatment the patient actually received. Results: Currently, RS results on 84 patients are available. Patient age range is 33–82 years. There are 56 (67%) N0 pts and 28 (33%) N+. Overall, 37 (44%) women had low, 36 (43%) intermediate and 11 (13%) high RS. The RS changed the initial treatment recommendations in 20 (24%) patients. Of the 34 patients initially recommended CTx+H, there was a shift to H alone for 12 (35%), whilst of the 50 patients initially recommended H alone, 8 (16%) shifted to CTx+H. A shift in treatment recommendations was reported for 8/37 (22%) pts with low, 8/36 (22%) with intermediate and 4/11 (36%) with high RS. 13/56 (23%) of N0 pts had a change in recommendation, whilst 7/28 (25%) N+ pts changed (table 1). 5 patients have decided against the final MDC recommendations: 3 chose CTx+H after recommendation of H (RS of 13,19 and 21 respectively), and 2 declined a CTx+H recommendation (RS of 19 and 25). Conclusion: Early results of our Australian study suggest an impact of Oncotype DX RS on adjuvant treatment decision making in the MDC setting. Updated results on the full 150 patients will be presented at the meeting. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-09-18.