Impact of Oncotype DX Recurrence Score on the Patterns of Locoregional Recurrence in Breast Cancer (Korean Radiation Oncology Group 19-06)

The current study evaluated the impact of the Oncotype DX recurrence score (RS) on the patterns of locoregional recurrence (LRR) in node-negative, hormone receptor-positive/human epidermal growth factor receptor 2-negative breast cancer. Totally, 339 patients from 4 institutions were enrolled and analyzed retrospectively. All patients underwent breast-conserving surgery followed by whole-breast irradiation; only 2 patients received regional nodal irradiation (RNI). The RS was < 11 in 55 patients, 11–25 in 241, and > 25 in 43. Sixty-two patients received adjuvant chemotherapy. All patients except 4 received hormonal therapy. During a 62-month median follow-up, local recurrence was observed in 1 patient; regional recurrence, 3; and distant metastasis, 7. All LRRs were observed among patients with a RS > 25, resulting in a 5-year LRR rate of 7.3% in this subgroup. Regional recurrences developed in patients did not receive RNI initially. Thus, RNI might be effective for patients with a high RS.