Abstract P1-06-05: Clinical practice and mortality in patients with oncotype DX intermediate score: What do we know about the gray zone?
Authors: Ibraheem AF , Press D , Dezheng H , Olopade F 
Published: February 2018

Abstract
BACKGROUND: The 21 gene expression signature Oncotype DX (ODX) is a powerful predictor of disease outcome in early stage hormone receptor positive breast cancer. ODX can be used for better risk stratification of patients who may benefit from chemotherapy. ODX testing increases confidence in treatment decisions especially when ODX recurrence score (RS) is low or high. However, for the intermediate RS, decisions on receiving chemotherapy or not is a joint decision made by the physician and patient, in part because results from the TAILORx and RxPONDER randomized clinical trials addressing this very important clinical question has yet to be published.
OBJECTIVE: To examine “real world” oncology practice and survival outcome for breast cancer patients with ODX RS score in the intermediate range.
METHODS: A retrospective cohort of women diagnosed with early stage, hormone receptor positive breast cancer whose ODX score was in the intermediate range was established using the National Cancer Data Base (NCDB), 2009-2013. We assessed the relationship of overall survival with chemotherapy receipt and RS score using Cox proportional hazards models adjusted for patient characteristics, including age, race/ethnicity, grade, year of diagnosis, Charlson Co-morbidity Index, lymphovascular invasion, nodal involvement, tumor size, and histology. Intermediate RS score was analyzed as both continuous variable and categorical variables (18-20, 21-23, 24-26, and 27-30).
RESULTS: Of 24,945 females reported to have intermediate ODX score, 10,179 (41.4%) received chemotherapy. Receipt of chemotherapy depended on ODX score monotonically, ranging from 19.1% in patients with RS = 19 to 76.1% in patients with RS = 30. In total, 426 patients have died from all causes. Overall, chemotherapy receipt was associated with a statistically significant reduction in the risk of death (hazard ratio=0.77; 95% confidence interval [CI]: 0.62-0.96, p=0.02) in multivariable Cox model. RS score was statistically positively associated with increased risk of death, with one unit increment in RS corresponding to 6.2% increased mortality risk (95% CI 3.2%- 9.2%, p&lt;0.0001). Using a categorical scale, we found patients with intermediate ODX scores in RS 27-30 range had 1.64-fold increased risk of death (95% CI: 1.13-2.37) compared to patients with ODX scores in RS 18-20 range.. The association between ODX score and overall survival was more pronounced in women younger than 50 (hazard ratio per 1 unit increment = 1.28, 95% CI: 1.17-1.40) than in women 50 years or older (hazard ratio per 1 unit increment = 1.04, 95% CI: 1.01-1.07).
CONCLUSION: Our analysis revealed the ODX score in the intermediate range still has prognostic value for overall survival especially for young-onset breast cancer patients, which is independent of other clinopathologic factors. As we eagerly await results from randomized clinical trials, young women with intermediate RS should be counseled to consider more aggressive treatment including chemotherapy, ovarian function suppression or participation in ongoing clinical trials of CDK inhibitors to improve overall survival outcomes.
Citation Format: Ibraheem AF, Press D, Dezheng H, Olopade F. Clinical practice and mortality in patients with oncotype DX intermediate score: What do we know about the gray zone? [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-06-05.