Abstract P2-09-06: Meta-Analysis of the Decision Impact of the 21-Gene Breast Cancer Recurrence Score in Clinical Practice

Abstract

Abstract Background: The 21-gene Recurrence Score® (RS) is a clinically validated assay that predicts the likelihood of chemotherapy benefit and the risk of distant recurrence for individual patients with estrogen receptor positive (ER+), early stage breast cancer (ESBC). The 21-gene RS is included in the published guidelines of the National Comprehensive Cancer Network and American Society of Clinical Oncology as an adjuvant-treatment decision tool. Recently, university-led studies have reported approximately 17-27% decision impact of 21-gene RS in actual practice. We reviewed the published literature and conducted a meta-analysis of the impact of the 21-gene breast cancer RS on treatment recommendations and decisions in clinical practice. Method: Published cohort studies that reported the change in the recommendation or actual use of adjuvant chemotherapy (CTX) before and after the RS were included. Patients must be identified as ER+, LN-ESBC. Outcomes evaluated were: treatment decision change from 1) CTX plus hormone therapy to hormone therapy only or 2) hormone therapy-only to CTX plus hormone therapy. Actual treatment change was used when available. Reductions in the relative and absolute CTX use associated with the 21-gene breast cancer RS were computed with Review Manager 5 Version 5.0.24. (Copenhagen: The Nordic Cochrane Centre, the Cochrane Collaboration, 2008). Results: 7 published studies, with a total of 913 patients were included in the meta-analysis. 62% (566/913) of patients were recommended or received CTX prior to testing with the 21-gene RS. After RS testing, 29% percent (268/913) of patients were recommended or received CTX. The absolute reduction of CTX use associated with RS testing was 30% (95% CI [-40%, -21%]) The relative risk ratio is computed as a ratio, weighted by the sample size of each study, of (1) proportion of patients treated with CTX plus hormone therapy after 21-gene RS and (2) proportion of patients treated with CTX plus hormone therapy before 21-gene RS. The estimated relative ratio in CTX use before and after 21-gene assay is 49% (95% CI [41%, 58%]). One limitation of this analysis is the heterogeneity in the study designs of the published studies. Of the 7 available studies, 1 was a prospective physician survey; 6 were retrospective chart reviews. A second limitation of the study is in the consistency of reported outcomes. 4 studies reported the use of CTX after 21-gene breast cancer RS, whereas the remaining 3 reported the physicians’ treatment recommendations. Lastly, the meta-analysis does not capture the important benefit of the RS for patients who switch from no CTX to CTX when a high RS is obtained. Conclusion: The meta-analysis shows consistent overall reduction in AC with the adoption of the 21-gene breast cancer RS. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-06.