Abstract P5-06-24: Validation of the Johns Hopkins oncotype DX recurrence score estimator

Abstract

Abstract Objective Oncotype DX (ODX) is a 21-gene assay used to predict the benefit of adjuvant chemotherapy in hormone receptor-positive, HER2-negative, lymph node-negative breast cancer. However, the test is expensive and the incremental contribution of this assay to routinely available clinicopathological information and how to integrate that information to best inform clinical decision making is unknown. Several models have been developed to predict whether there are cases in which a clinician or patient could opt to forgo ODX because the outcome of the test might be predicted with a high degree of accuracy using routinely available measures. One such model was developed and validated at Johns Hopkins University. Here we used their recurrence score estimator to learn whether we could safely adopt the calculator for use at our institution to improve resource utilization. Methods An IRB-approved prospective database was created in 2010 for patients seen by a single medical oncologist at Rush University Medical Center and for whom oncotype DX was performed. From this database, patients were identified with HR+, HER2-negative, node-negative breast cancer and for whom age at diagnosis, tumor size, grade and Ki-67 were known. These data were entered into the Johns Hopkins breast cancer recurrence score estimator (http://www.breastrecurrenceestimator.onc.jhmi.edu). This model categorizes patients with a recurrence score (RS) of less than or equal to 25 as low risk and those with a score of greater than 25 as high risk. Results There were 189 patients. The mean age, tumor size, ER%, PR% and Ki-67% were 58 years old, 1.5 cm, 88%, 44% and 15% respectively. 14% had a RS greater than 25. The estimator assigned 65 patients to low risk, 59 of whom had a low RS and 6 with a high RS. The estimator assigned 4 patients to high risk, all of whom had a high RS. Conclusions The Johns Hopkins recurrence score estimator assigned 69 patients to low or high risk with 91.3% accuracy. Future analysis of a larger sample size is needed to optimize the accuracy of this estimator nationally. It may also be beneficial to separately analyze patients aged 50 or younger with an ODX score between 16 and 25 who had chemotherapy benefit in the TAILORx study in order to improve the utility of this risk estimator. Citation Format: Kristen Millado, Louis Fogg, Ritu Ghai, Melody Cobleigh. Validation of the Johns Hopkins oncotype DX recurrence score estimator [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-06-24.