Abstract
The purpose of this study was to determine if receipt of chemotherapy was associated with utilization of the 21-gene recurrence score assay (RS assay) or with recurrence score (RS) in eligible patients. Using the National Cancer Data Base (NCDB), we identified female patients eligible for RS assay based on National Comprehensive Cancer Network (NCCN) guidelines: age 18–70, ER-positive and HER2-negative early-stage breast cancer diagnosed during 2010–2013. We excluded patients not meeting testing guidelines. Inclusion required result of RS in patients who underwent RS assay and status for receipt of chemotherapy. Multivariable logistic regression models and propensity matched analysis were used to determine associations between RS assay and RS with receipt of chemotherapy. Among 129,765 patients who were eligible, 74,778 underwent RS assay and had results available. Of these, 59.5 % (44,505) had low-risk, 32.0 % (23,920) had intermediate-risk, and 8.5 % (6353) had high-risk RS. Patients with intermediate- and high-risk RS were more likely to receive chemotherapy [OR 12.9 (CI 12.2–13.6), p <0.001 and OR 87.2 (CI 79.6–95.6), p <0.0001], respectively. In both low- and intermediate-risk groups, increasing RS score was significantly associated with increasing odds of receiving chemotherapy [OR 1.10 (CI 1.09–1.12), p <0.0001 and OR 1.26 (CI 1.25–1.27), p <0.0001, respectively, for each point increase in RS]. Receipt of chemotherapy was more likely in patients who did not undergo RS assay compared to those who did, OR 1.21 (CI 1.175–1.249) p <0.0001. The utilization of RS assay and the RS were both strongly associated with chemotherapy receipt. Patients eligible for chemotherapy, based on NCCN criteria, were more likely to receive chemotherapy if they did not undergo RS assay or they had a high RS.
Highlights
The use of predictive and prognostic multigene signature testing (MGST) to aid in clinical decision-making regarding adjuvant systemic therapy for breast cancer patients has increased in the last decade as they have been incorporated into clinical guidelines [1]
A confirmatory analysis based on 1:1 propensity score matching showed a similar significant association between lack of recurrence score (RS) assay and receipt of chemotherapy [OR 1.18 (CI 1.15–1.22), p \0.0001 via Pearson’s v2 test], with patients well matched with no significant differences in patient tumor and demographic characteristics shown previously in Tables 1 and 2. This is the largest registry-based study focused on the relationship between utilization of the RS assay, RS, and receipt of chemotherapy, in chemotherapyeligible, early-stage breast cancer patients
In addition to another year of data collection, our study provides a focused propensity matched analysis on chemotherapy receipt in contrast to a recently published study evaluating National Cancer Data Base (NCDB) data which provided a broad survey of therapeutic implications and disparities associated with the RS assay [12]
Summary
The use of predictive and prognostic multigene signature testing (MGST) to aid in clinical decision-making regarding adjuvant systemic therapy for breast cancer patients has increased in the last decade as they have been incorporated into clinical guidelines [1]. MGST is included in the National Comprehensive Cancer Network (NCCN) guidelines for patients with ER-positive and HER2-negative tumors who have undergone resection and are candidates for chemotherapy [3]. The utility of RS assay for this purpose has been evaluated in retrospective and prospective clinical trials [2, 4, 5]. The impact of this test on chemotherapy prescribing outside of clinical trials
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