Abstract P2-08-24: The average modified Magee score can be helpful in predicting an Oncotype DX recurrence score ≤ 25

Abstract

Abstract Introduction: The recent TAILORx results suggests that adjuvant endocrine therapy and chemoendocrine therapy had similar efficacy in women with hormone–positive, HER2-negative, axillary node–negative breast cancer who had an Oncotype Dx recurrence score (ODXRS) between 11 and 25. These findings, along with updated results that patients with an ODXRS < 11 have a 9-year recurrence rate of only 3%, suggest that certain populations of patients with an ODXRS ≤ 25 may not benefit from additional systemic chemotherapy. Oncotype Dx is an expensive test (current list price of $4,650.00), and cost has been an impediment to its adoption in many centers throughout the United States, and internationally. The test can be performed only at a commercial specialized laboratory. Based on a modification of the new Magee equations (Klein ME, et al. Mod Pathol. 2013;26(5):658–664) we published an algorithm based on 283 patients with ODXRS's (Turner BM, et al. Mod Pathol. 28(7):921-31) that suggested our algorithm offered a less expensive alternative to Oncotype DX testing. We have validated this algorithm in a multi-institutional study on an additional 619 patients with ODXRS's (in preparation for publication). Our validation data, and our data from the original study, also suggests that the average modified Magee equation can reliably predict patients who will have an ODXRS ≤ 25. Methods: 903 cases with an available ODXRS (2006-2018) were identified from the pathology files at the University of Rochester Medical Center (n = 752) and the University of Louisville (n = 151). Information required to calculate the average modified Magee score, which includes estrogen receptor (ER) and progesterone receptor (PR) status, Her-2 status, Nottingham score, tumor size, and Ki-67 were also extracted from the medical record. 78 patients did not have an available Ki-67, leaving 825 patients for inclusion in this study. Results: 478/488 (98%) patients with an average Modified Magee score ≤ 18 had an ODXRS ≤ 25 (only 2% had an ODXRS > 25 - Table 1). 125/337 (37%) patients with an average Modified Magee score >18 had an ODXRS > 25 (Table 1) . Conclusions: The average Modified Magee Score can be helpful in predicting an ODXRS ≤ 25. Patients with an average Modified Magee score ≤ 18 may not need to be sent out for Oncotype Dx testing. The potential cost savings to the health care system would be enormous. Table 1:Average Modified Magee score and risk of an Oncotype Dx recurrence score (ODXRS) > 25Magee scorenAverage ODXRSMinimum ODXRS valueMaximum ODXRS valueCases with ODXRS > 25 [n (%)]≤ 91811.02190 (0)102110.90261 (4.8)113712.10250 (0)126012.00281 (1.7)136412.00230 (0)147012.90271 (1.4)156513.61313 (4.6)165614.12292 (3.6)175214.50272 (3.8)184514.30250 (0)195418.96379 (16.7)204319.30348 (18.6)215921.193715 (25.4)223819.32496 (15.8)232523.383811 (44)242920.83329 (31)252325.0144011 (47.8)> 25-272729.2174620 (74.1)> 27-301634.9225113 (81.3)> 302345.7317823 (100)≤ 1848812.903110 (2)> 1833723.7078125 (37) Citation Format: Turner BM, Sanders MA, Breaux A, Soukiazian A, Soukiazian N, Hicks DG. The average modified Magee score can be helpful in predicting an Oncotype DX recurrence score ≤ 25 [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-24.