Introduction: The 21-gene recurrence score (RS) has been extensively studied and validated in patients with estrogen receptor-positive (ER + ), human epidermal growth factor 2 (HER2)-negative breast cancer; however, RS testing is not routinely performed in patients with HER2-positive (HER2 + ) disease. We sought to determine patterns of RS testing, to characterize RS distributions, and to determine the impact of RS results on clinical decision-making for patients with ER + , HER2 + breast cancer. Materials and Methods: Using the Surveillance and Epidemiology End Results program database, we identified women with ER + , HER2 + breast cancer. We stratified patients using TAILORx RS cutoffs and evaluated treatment characteristics across patients. Multivariable logistic regression was performed to determine factors associated with RS testing and receipt of a high-risk RS. Results: Overall, 5% of patients with ER + , HER2 + , early stage breast cancer underwent RS testing. The distribution of RS testing by TAILORx cutoffs were: high-risk, 17%; intermediate-risk, 49%; and low-risk, 34%. Chemotherapy utilization among those not tested was 66%. Among those tested, utilization was significantly associated with RS results: 67% of high-risk, 30% of intermediate-risk, and 19% of low-risk patients received chemotherapy. Progesterone receptor-negative status, larger tumor size, and high tumor grade were significantly associated with high-risk RS. Conclusions: RS testing is used sparingly among patients with HER2 + early-stage breast cancer; however, test results appear to impact clinician's decision-making on chemotherapy use.
Bibliographical noteFunding Information:
The authors would like to acknowledge Stephanie Lundgren and the Department of Surgical Oncology for their assistance with this manuscript. This project was in part funded by the Institute for Basic and Applied Research in Surgery and the VFW fund of the University of Minnesota .
© 2018 Elsevier Inc.
Copyright 2019 Elsevier B.V., All rights reserved.
- Breast cancer
- Recurrence score testing