Abstract P4-08-33: The significance of Oncotype DX recurrence score in T1-2N1M0 ER positive HER2 negative breast cancer: An analysis combined with the prognostic stage in the updated AJCC 8th edition

Abstract

Abstract Purpose: Oncotype DX recurrence score (Oncotype DX RS) is applied in the prognostic stage in T1-2N0M0 ER+/HER2- breast cancer. But its significance is unclear in cases with T1-2N1M0 ER+/HER2- disease. Our study was to evaluate the prognostic significance of Oncotype DX RS in combination with the prognostic stage in the updated AJCC 8th edition. Methods: The Surveillance, Epidemiology, and End Results (SEER) database was searched to identify invasive ductal breast cancer cases in T1-2N1M0 stage with ER positive HER2 negative status and Oncotype DX RS diagnosed between 2004 and 2012. Patients with unknown histologic grade or PR status, no or unknown surgery performed, or less than 6 months of follow up were excluded. Patients with RS 0-10, 11-25, >25 were categorized into low risk, midrange risk and high risk groups respectively. Comparisons of the distribution of RS groups among prognostic stages were performed using Pearson's chi-square. Breast cancer-specific survival (BCSS) and overall survival (OS) were estimated using the Kaplan-Meier method and compared across RS groups using the log-rank statistic. Cox models were fitted to compare the association between RS groups, prognostic stages and BCSS or OS after adjusting for other characteristics. Results: Altogether 4059 cases were enrolled, which were categorized into prognostic stage IA-IIIA (only 357 cases in stage IIB and 35 cases in stage IIIA). More than 60% cases in prognostic stage IA-IIA had their RS in midrange risk group. There were decreasing proportion of low risk RS group and increasing proportion of high risk RS group with the ascending of prognostic stages (P<0.001). The median follow up was 59 months. There were significant differences in BCSS and OS among RS groups (log-rank P<0.001). In the subgroup analysis, there were also significant differences in BCSS and OS among RS groups in prognostic stages IA-IIA. In the multivariate Cox analysis, the RS group was an independent prognostic factor for BCSS (midrange risk vs. low risk, HR=3.647, 95% CI: 1.124-11.837, P=0.031; high risk vs. low risk, HR=15.372, 95% CI: 4.600-51.374, P<0.001) and OS (midrange risk vs. low risk, HR=1.718, 95% CI: 1.039-2.840, P=0.035; high risk vs. low risk, HR=4.225, 95% CI: 2.462-7.251, P<0.001) along with the prognostic stage. Conclusions: Oncotype DX RS has prognostic significance in T1-2N1M0 ER+/HER2- disease. Further prospective research is warranted. Citation Format: Chen H, Wang M, Zhang P, Zhang M, Wu K. The significance of Oncotype DX recurrence score in T1-2N1M0 ER positive HER2 negative breast cancer: An analysis combined with the prognostic stage in the updated AJCC 8th edition [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 P4-08-33.