2914 - Accelerated Partial Breast Irradiation in Early-Stage Breast Cancer Patients with High Oncotype DX Scores: An Institutional Retrospective Review
Presenter(s)
K. Wang1, Y. Gokun2, J. Eckstein3, T. Y. Andraos1, R. Young1, S. Beyer4, and S. R. Jhawar5; 1Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, 2Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH, 3Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH, 4Department of Radiation Oncology, James Cancer Hospital/Wexner Medical Center, The Ohio State University, Columbus, OH, 5Department of Radiation Oncology, The James Cancer Center, Ohio State University Wexner Medical Center, Columbus, OH
Purpose/Objective(s):
Accelerated partial breast irradiation (APBI) is an established treatment option for selected patients with early-stage breast cancer after breast conserving surgery. The Oncotype DX assay is a 21-gene expression test that generates a recurrence score between 0-100, providing prognostic information regarding distant recurrence risk and predictive information regarding chemotherapy benefits in estrogen receptor-positive, Her2-negative early-stage breast cancer. However the safety of APBI in patients with elevated Oncotype DX scores remains unclear. We conducted an institutional retrospective review to evaluate clinical outcomes of patients with high (16 or above) vs low (below 16) oncotype DX scores treated with APBI.Materials/Methods:
We identified patients with hormone receptor-positive, Her2-negative, node-negative early-stage invasive breast cancer who underwent breast-conserving surgery followed by APBI at our institution between January 2013 and February 2024. Patients were stratified by Oncotype DX into low-risk and high-risk cohorts according to a cutoff of 16. Demographic and clinicopathologic characteristics, treatment variables and radiation parameters were collected. Primary endpoint was progression-free survival (PFS). Secondary endpoint was overall survival (OS). Wilcoxon Rank Sum Test and Chi-Square Test were used for bivariate comparisons between low-risk and high-risk cohorts. Survival outcomes were analyzed using Kaplan-Meier method with Log Rank Test.Results:
A total of 203 patients met the inclusion criteria, including 120 (59.1%) patients with low oncotype DX score and 80 (40.9%) with high oncotype DX score (range=0-48). Patients with high oncotype DX scores are more likely to have ILC tumor histology and to receive adjuvant chemotherapy (p<0.05). Median follow-up was 43.6 months (range: 6.7-84.4). No significant differences were observed in PFS or OS between groups. There were a total of 6 deaths among the 203 patients. Survival was excellent in both cohorts.Conclusion: In this single institution retrospective review, early stage breast cancer patients with high Oncotype DX scores treated with APBI demonstrated comparable local control and survival outcomes to those with low scores. These findings suggest that genomic risk stratification alone may not preclude consideration of APBI in appropriately selected patients. Prospective studies are warranted to further define the role of APBI in genomically high-risk populations.