Impact of Oncotype DX Recurrence Score on Treatment Selection and Survival in Early-Stage Hormone Receptor-Positive Breast Cancer

Abstract

Objective: Breast cancer incidence has nearly doubled in recent years, making it the most diagnosed cancer among women. This study investigates the role of the Oncotype DX assay in treatment decision-making and its impact on survival outcomes for patients with early-stage, hormone receptor-positive, node-negative breast cancer.

Methods: This retrospective cohort study (2015–2025) at Hiwa Oncology Hospital analysed female patients with early-stage (T1/T2), HR+/HER2−, node-negative (N0) breast cancer who underwent Oncotype DX testing. Inclusion required available recurrence scores (RS) (categorised as low [RS 0–10], intermediate [RS 11–25], or high [RS ≥26]) and adjuvant chemotherapy eligibility. Data included demographics, tumour characteristics (grade, subtype, Ki-67, etc.), conventional clinical risk classification, treatment details (surgery, systemic therapy), and outcomes (overall survival, recurrence). Statistical analysis employed descriptive statistics, chi-square tests, and Kaplan-Meier survival curves with log-rank tests using SPSS v27.

Results: Among 294 HR+/HER2− breast cancer patients, Oncotype DX classified 60.5% as intermediate-risk, 21.5% high-risk, and 18.0% low-risk. Discordance with clinical risk classification was observed (p=0.091): 52.8% of Low Oncotype DX-risk patients were High clinical risk versus 31.7% of High-DX-risk patients classified Low clinically. High-risk patients exhibited higher ductal histology (98.4%; p=0.010), grade III tumours (41.3%; p<0.001), LVI (27.0%; p=0.031), Luminal B (93.7%; p<0.001), and Ki-67 >14% (93.7%; p<0.001). Chemotherapy use varied dramatically (low-risk: 1.9% vs. high-risk: 95.2%; p<0.001). Five-year survival was 100% (low/intermediate) vs. 96.8% (high-risk; Log Rank p=0.025).

Conclusion: It appears that utilising Oncotype DX risk categorisation serves as a more appropriate criterion for treatment decision-making compared to conventional risk classification, owing to its superior prognostic prediction for patients. Oncotype DX-guided therapy may reduce unnecessary adjuvant chemotherapy administration.