Cost analysis of using Magee scores as a surrogate of Oncotype DX for adjuvant treatment decisions in women with early breast cancer

Breast cancer is the most common cancer in women worldwide. Most current guidelines recommend using multigene profiling assays to aid the decision on the addition of chemotherapy to adjuvant hormone therapy for women who present with early-stage, hormone receptor-positive, HER2-negative disease. One of these assays is the Oncotype DX, which predicts the disease recurrence risk and adjuvant chemotherapy benefits. Given its high cost, there is an economic incentive to evaluate its surrogates, such as the Magee equations. We assessed health system costs associated with the use of the Magee scores. A probabilistic decision tree was used to calculate the difference in mean health system costs based on data obtained from a randomized trial and the published literature. Costs were calculated from a perspective of Canada's publicly funded health care system. A series of sensitivity analysis was conducted to assess the robustness of the study findings. The Magee equations were associated with a total cost savings of C$100 per patient (95% CI, -C$3068 to C$5022) compared with standard of care. The difference in costs was highly sensitive to the extent that the Magee scores could reduce the frequency of adjuvant chemotherapy and Oncotype DX requests.