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.
Keywords: 21-gene assay; C; C6; C63; Cost-effectiveness; D; D6; D61; breast cancer; chemotherapy; multigene assay; the Oncotype DX test.