Characterization of oncotype DX recurrence score and chemotherapy utilization patterns in young women (<= 40) with early stage ER plus /HER-, lymph node negative breast cancer

Background: Meta-analyses have demonstrated that young women ≤40 (YW) derive the most benefit from chemotherapy (EBCTCG, Lancet. 1998). Oncotype DX was designed to determine the benefit of chemotherapy in women with ER+/HER2-, node-negative (LN-) breast cancer based on recurrence score (RS). TAILORx reported clinically meaningful benefits in freedom-from-distant recurrence in women Methods: Using the National Cancer Data Base (NCDB), we identified individuals age 25) RS. Age categories were classified as ≤40, 41-50, and \u003e50. Chi-square tests or Fisher’s exact tests were used to compare categorical variables. Logistic regression was used to estimate the association of RS score and age group with adjuvant chemotherapy use, after adjustment for known covariates. Kaplan-Meier curves were used to visualize unadjusted overall survival (OS), and Cox proportional hazards models were used to estimate adjusted OS. Results: 120,051 women were identified, of whom 4,781 were ≤40 years, 24,846 were 41-50, and 90,424 were \u003e50. By age group, 20% of YW had a high RS compared to 12% of women age 41-50 and 15% of women \u003e50 (p 50 to receive chemotherapy (p Conclusions: High RS is more common in YW (≤40) than those age 41-50 or \u003e50, and is associated with worse OS. YW with an int or low RS are more likely to receive chemotherapy despite unclear benefit. Chemotherapy was omitted in over half of YW with RS of 16-25, highlighting the uncertainty in clinical practice which will remain until further studies inform optimal systemic treatment specific to YW. 1. Sparano, J.A., et al., Clinical and Genomic Risk to Guide the Use of Adjuvant Therapy for Breast Cancer. New England Journal of Medicine, 2019. 380(25): p. 2395-2405. Citation Format: Sarah Sammons, Yi Ren, Jeremy Force, Oluwadamilola M. Fayanju, Laura H. Rosenberger, Jennifer K. Plichta, Gretchen Kimmick, Kelly Westbrook, Susan Dent, Carey Anders, Samantha M. Thomas, Terry Hyslop, E. S. Hwang, P. K. Marcom, Rachel A. Greenup. Characterization of oncotype DX recurrence score and chemotherapy utilization patterns in young women (≤40) with early stage ER+/HER-, lymph node negative breast cancer [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 P3-08-10.