Treatment Outcomes according to the EndoPredict Score in ER-Positive, HER2-Negative Early Breast Cancer

Purpose: The purpose of this study was to evaluate the treatment outcomes of estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER+/HER2−) breast cancer according to the risk group using EndoPredict (EP) score. Patients and Methods: Between 2015 and 2019, 207 patients with ER+/HER2− pN0-N1 early breast cancer who underwent surgery, EP test, and adjuvant radiotherapy were accrued. The EPclin score, which combines the molecular EP score with nodal status and tumor size, was calculated, and patients were divided into EPclin low- or high-risk groups by the cutoff value of 3.3. Results: There were 154 and 53 patients in the EPclin low- and high-risk groups, respectively. Forty-one patients (81.1%) of the high-risk group received adjuvant chemotherapy, while only 1 (0.6%) of the low-risk group did. With a median follow-up of 54.1 months (range 8.2–76.6), the 5-year disease-free survival rates of low- and high-risk groups were 100% and 88.9%, respectively (p < 0.001). Conclusions: The EPclin score was associated with recurrences in ER+/HER2− early breast cancer.