The impact of the Oncotype Dx breast cancer assay in clinical practice: Systematic review and meta-analysis.

Abstract

560 Background: Many studies have evaluated the Oncotype Dx Breast Cancer Assay (ODX) and its impact on adjuvant chemotherapy (ACT) treatment decisions. However, it can be difficult for clinicians and other stakeholders to interpret the collective findings of these studies, as they were conducted in diverse settings and have limited sample sizes. To address this issue, we conducted a systematic review and meta-analysis to synthesize ODX results and provide insights about the utility of ODX in actual clinical practice. Methods: We performed a systematic review of ODX studies using PubMed, Embase, ASCO, and SABCS. Studies were included if patients had ER +, node -, early stage breast cancer, reported use of ODX to inform actual ACT decisions, and reported outcomes of interest, including: 1) distribution of ODX recurrence scores (RS); 2) impact of ODX on ACT recommendations; 3) impact of ODX on ACT use; and 4) proportion of patients following the treatment suggested by the ODX RS. Results: A total of 28 studies met inclusion criteria. The distribution of RS categories was 48.8% low, 39.0% intermediate, and 12.2% high (21 studies, 4,156 patients). ODX changed the clinical-pathological ACT recommendation in 33.4% of patients (8 studies, 1,437 patients). In patients receiving ODX, receipt of ACT was: 28.2% overall, 5.8% low, 37.4% intermediate, and 83.4% high. High RS patients were significantly more likely to follow the treatment suggested by ODX vs. low RS patients RR: 1.07 (1.01–1.14). Conclusions: The pooled results for the impact of ODX on ACT recommendations are consistent with most individual studies to date. However, the proportion of intermediate RS results is nearly 2-fold higher than reported in the ODX development studies by Paik et al., which may have implications for the clinical utility and cost impacts of testing. Also, high RS vs. low RS patients were more likely to follow the ODX results, suggesting a tendency toward aggressive treatment despite a low ODX RS. Finally, there was a lack of studies on the impact of ODX on ACT use vs. standard approaches, suggesting additional studies are warranted. [Table: see text]