Abstract P2-05-30: OncotypeDX® for breast cancer: A multigene assay that makes a difference?
Authors: Martel S , Prady C , Simon R , Matte C 
Published: March 2017

Objective: OncotypeDX® (ODX) is a multigene diagnostic assay that can estimate the 10 year-risk of distant recurrence in women with hormone receptor positive (HR+) and node negative (N–) early breast cancer. The testreports a Recurrence Score® (RS) and three risk group categories have been described: low-risk (&lt;18), intermediate-risk (18-30) and high-risk (≥31). It helps the oncologist in the adjuvant chemotherapy decision process and globally leads to a reduction in the recommendation for chemotherapy use. This test is expensive and represents an economic burden in a publicly funded province. Nonetheless, its use has been approved over other gene expression profiling like Mammaprint® based on the evidence of its prognostic and predictive ability. We evaluated the adequacy of the requests for the ODX in an academic setting after the introduction in May 2012 of a reference framework for its use in Québec, Canada and the impact on chemotherapy recommendation. The costs generated by the test were also determined. Methods: We included all patients with an ODX request from two University Centers, CICM and CHUS, and estimated the concordance with the current provincial guideline for which an ODX may be ordered (invasive breast cancer HR+/Her2–/N- that is T1b with unfavorable characteristics or T1c or T2). For the intermediate-risk group, the factors influencing the final decision to use systemic chemotherapy were analysed. The projected cost-effectiveness of the ODX was derived from the proportion of patients (pts) for which the chemotherapy was not recommended. Results: Between May 2012 and December 2014, a total of 201 pts, 123 pts from CICM and 78 from CHUS, had an ODX done. In 93,0% (95%CI, 89,5-96,6) of pts, ODX was ordered correctly with respect to the guideline. There was no statistical differences between both sites (CICM: 92,7% [95%CI, 97,3-88,1]; CHUS 93,6% [95%CI, 88,2-99,0]). A total of 9 pts had high-risk RS (4,5%), 78 pts had intermediate-risk RS (38,8%) and 112 pts had low-risk RS (55,7%). Chemotherapy was recommended for 31 pts (18,2%) instead of an estimated 58,0% prior to the use of ODX according to previous reports published. In the intermediate-risk group, the majority of pts (74,4%) did not receive chemotherapy. The patient's preference and the absence of a proven benefit were the main reasons for withholding chemotherapy in this group. The additional cost associated with the use of the ODX was compensated with the reduction of the adjuvant systemic chemotherapy prescribed and its derived expenses (chemotherapy cost, nursing time and hospitalisations) and savings of 100 K were observed. Conclusions: In early breast cancer HR+ and N-, the use of ODX in two University Hospitals is concordant with published recommendations. ODX use is cost effective. This benefice does not take into account the psychological burden that comes with the decision to use adjuvant chemotherapy; neither does it evaluate potential long term complications. The widespread use of ODX must be looked at critically in face of other emerging gene signature tests like Endopredict® and PAM50®. As for the predictive ability of the ODX for adjuvant chemotherapy, one can question the strength of the actual evidence and argue if it confers this test an advantage over other multigene assays.

Citation Format: Martel S, Prady C, Simon R, Matte C. OncotypeDX® for breast cancer: A multigene assay that makes a difference? [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-05-30.