ABSTRACT
Background: The 21-gene assay (the Oncotype DX Breast Recurrence Score® test) is a validated multigene assay which produces the Recurrence Score® result (RS) to inform decisions on the use of adjuvant chemotherapy in human epidermal growth factor receptor 2-negative (HER2-), hormone receptor positive (HR+) early invasive breast cancer. A model-based economic evaluation estimated the cost-effectiveness of the 21-gene assay against the use of clinical risk tools alone based on the latest evidence from prospective studies. Methods: The proportion of patients assigned to chemotherapy conditional on their RS result was obtained from retrospective data from the Clalit registry. The probability of distant recurrence with endocrine and chemo-endocrine therapy conditional on RS result was obtained from TAILORx and NSABP B-20 trials. The cost-effectiveness of the 21-gene assay compared to using clinical risk tools alone was estimated in terms of cost per quality-adjusted life-year (QALY) over a lifetime horizon. Results: The 21-gene assay was more effective (0.17 more quality-adjusted life years) at a lower cost (-£519) over a lifetime compared to clinical risk alone. The model results were sensitive to assumptions around the magnitude of benefit of chemotherapy in the high RS result subgroup. Other assumptions underpinning the model, such as the proportion of patients assigned to chemotherapy in the low and mid-range RS result subgroups and long-term distant recurrence probabilities, had a smaller impact on the results. Conclusion: The analysis showed that the cost-effectiveness of the 21-gene assay is sensitive to assumptions for chemotherapy sparing for patients with RS 0-25 whose outcomes with endocrine therapy are no worse compared to chemotherapy-assigned patients, and a chemotherapy benefit in the RS 26-100 group. Future studies need to incorporate a wider set of tumour profiling tests other than the 21-gene assay to allow a direct comparison of their cost-effectiveness.
ABSTRACT
AIMS: Given the high rate of adverse events and high cost of adjuvant chemotherapy, it is optimal to avoid its use when endocrine therapy is equally effective at preventing distant recurrence of early breast cancer. The Oncotype DX test is a predictive and prognostic multigene assay used to guide adjuvant chemotherapy decisions in early breast cancer based on a Recurrence Score (RS) result. A model-based cost-effectiveness analysis compared the Oncotype DX test to clinical risk tools alone for HR+/HER2- node-positive (1-3 axillary lymph nodes) early breast cancer patients based on results from the RxPONDER trial. MATERIALS AND METHODS: A decision-tree and Markov model was developed in Microsoft Excel. Distributions of patients and distant recurrence probabilities with endocrine and chemo-endocrine therapy were derived from the RxPONDER trial, TransATAC and SWOG-8814. Chemotherapy assignment data were obtained from the Clalit registry. The cost of adjuvant chemotherapy was based on the distribution of treatments used in the UK combined with published drug unit costs in the UK. The cost of distant recurrence and health state utility values were obtained from literature. RESULTS: The Oncotype DX test was found to be more effective (with an estimated 0.02 additional QALYs) at a lower estimated cost (-£989) compared to clinical risk tools alone. The results did not substantially change with more conservative clinical and cost scenarios. The RxPONDER trial was restricted to RS 0-25, and data synthesis with other studies was required to inform the analysis, which increased uncertainty. CONCLUSIONS: The Oncotype DX test is highly likely to be cost-effective in node-positive early breast cancer. The results were driven by reduction in the use of chemotherapy with consequence avoidance of the costs and harmful effects of chemotherapy. Targeted treatment of a minority (11%) of women with RS 26-100 who benefit from chemotherapy reduced cost and improved survival.
