Background: Multigene assays (MGA), such as the Oncotype DX Breast Recurrence Score® test, are used to guide adjuvant treatment decisions in hormone receptor positive (HR+), human epidermal growth factor 2 negative (HER2-) early breast cancer. As reported in multiple randomized studies including the TAILORx and RxPONDER trials, the Oncotype DX test can identify patients with ER+/HER2- disease who can safely be spared chemotherapy. Furthermore, adjuvant chemotherapy for patients with RS 26-100 reduces the risk of distant recurrence. As part of a study to adapt a Oncotype DX test cost-effectiveness model to the US market, we sought to estimate the costs of treatment for HR+/HER2- early breast cancer in the US. Methods: The distributions of drug treatments used in the adjuvant and metastatic breast cancer setting were obtained from breast cancer specialists in the US and published literature. These were combined with dosage schedules from NCCN guidelines and published unit costs to estimate the costs associated with therapy. The cost of treating short-term adverse events (AEs) due to chemotherapy was derived from published literature, which combined the frequency of AEs with the cost of treatment for individual AEs. Costs of distant recurrence were estimated based on the mean length of subsequent line chemotherapy treatments obtained from literature. Drug and administrative costs were based on published Medicare fee schedules and presented in 2020 US dollars. Results: The mean difference in costs of treatment between adjuvant chemo-endocrine therapy and endocrine therapy alone in patients with node negative and node positive ER+/HER2- disease were $12,618 and $17,564, respectively (Table 1). The key drivers were G-CSF costs. The weighted average cost of treatment for distant recurrence (across therapies used in the advanced setting) was $175,386 and $91,646 for first-line and second-line treatments, respectively, driven mainly by the use of CDK4/6 inhibitors. Conclusion: The costs associated with adjuvant chemotherapy for HR+/HER2- early breast cancer are substantial. The current use of novel treatments for advanced breast cancer has significantly increased the cost of managing distant recurrence. This highlights the importance of accurately capturing the downstream cost consequences in economic evaluations of MGAs. The cost estimates reported here will inform an updated cost-effectiveness analysis of the Oncotype DX test in the US healthcare system.
HSR22-129 Table 1. Mean costs of adjuvant chemo-endocrine therapy by nodal status