-Original-

The Indication of Adjuvant Therapy Based on Oncotype DX Recurrence Score in Relation to Clinical and Pathological Factors, and Survival: A Retrospective Analysis of Real-World Use

Hideki Asakawa^1,2, Asuka Nakamura², Yuki Yanagawa², Takashi Shigekawa² and Hiroyuki Takei¹

¹Department of Breast Surgery and Oncology, Nippon Medical School, Tokyo, Japan
²Department of Breast Surgery and Oncology, Tokyo Kyosai Hospital, Tokyo, Japan

Background: Oncotype DX is an important tool for guiding perioperative treatment in estrogen receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Real-world retrospective studies are essential for validating its clinical utility.
Methods: We retrospectively evaluated the association of Oncotype DX Recurrence Score (ODRS) with clinical and pathological characteristics, chemotherapy regimen, and recurrence-free survival (RFS) in consecutive patients with ER-positive/HER2-negative primary breast cancer.
Results: A total of 133 patients underwent Oncotype DX testing to determine the need for adjuvant chemotherapy. Mean age was 49.2 years, 67.7% of the patients were premenopausal, and 50.4% had nodal metastases. Mean ODRS was 19.5. Patients were categorized into three risk groups: low (ODRS 0-15, 40.6%), intermediate (16-25, 36.1%), and high (≥26, 23.3%). ODRS was significantly correlated with histologic grade, ER, PgR, and Ki-67. Endocrine therapy alone was administered to all low-risk patients. Chemotherapy was administered to 20.8% of patients at intermediate risk and 67.7% of patients at high risk. Multivariate analysis confirmed that ODRS was the strongest predictor of chemotherapy administration. During a median follow-up of 30.4 months, three distant recurrences occurred (in two intermediate-risk patients and one high-risk patient). No recurrence was observed in the low-risk group. RFS was worse in higher ODRS categories.
Conclusions: Real-world data demonstrate that ODRS correlates with key pathological characteristics and can guide adjuvant therapy selection, independent of menopausal status or nodal involvement. This suggests that ODRS is useful in tailoring chemotherapy decisions in ER-positive/HER2-negative breast cancer.

J Nippon Med Sch 2026; 93: 225-235

Keywords
adjuvant therapy, breast cancer, oncotype DX, premenopausal women, recurrence-free survival

Correspondence to
Hideki Asakawa
hideki-asakawa@nms.ac.jp

Received, December 8, 2025
Accepted, December 22, 2025