原句：Pathologic complete response (pCR) after Primary Systemic Treatment (PST) for breast cancer is associated with excellent long-term outcomes. With increasing use of PST, the indication for regional nodal irradiation (RNI) has been challenged. The aim of this paper is to review the literature on de-escalation of RNI in patients treated with PST. We found no level 1 evidence on de-escalation of RNI after PST, but several randomized trials are ongoing. Consequently, current de-escalation strategies are based on cohort studies. These studies showed that in patients with low nodal tumour burden (LNTB) (≤3 suspicious nodes at imaging) prior to PST, and ypN0 based on Axillary Lymph Node Dissection (ALND), omission of RNI resulted in very low regional recurrences (RR) without compromising survival. In patients with LNTB and ypN0 based on Sentinel Lymph Node Biopsy (SLNB), omission of axillary treatment also resulted in low RR; the majority of these patients received local radiotherapy. Similarly, in patients with ypN1 (ALND) disease, omission of RNI resulted in low 5-year RR rates. Low RR-rates were also found in the few studies replacing ALND by RNI, in patients with ypN1 (SLNB) disease. In patients with high nodal tumour burden prior to PST and ypN0 (SLNB), replacing ALND by RNI also resulted in low RR. Due to the limited number of patients, these data should be interpreted with caution. We conclude that although level 1 evidence is lacking, de-escalation of RNI after PST can be considered in selected cases. 乳腺癌。经过原发性全身治疗 (PST) 后病理学完全缓解 (pCR) 与出色的长期结果相关。随着 PST 的日益普及，区域淋巴结放射治疗 (RNI) 的适应症受到挑战。本文的目的是回顾 PST 接受者中 RNI 逐步减少的文献。我们未发现关于 PST 后 RNI 逐步减少的一级证据，但有多项随机试验正在进行中。因此，目前的减少战略是基于队列研究。这些研究表明，当 PST 前淋巴结肿瘤负荷低 (LNTB) （影像学可疑结节≤3个）且根据腋窝淋巴结清扫 (ALND) 确定 ypN0 时，省略 RNI 可使区域复发 (RR) 非常低而不影响生存率。在 LNTB 和 ypN0（通过前哨淋巴结活检 (SLNB) 确定）的病人中，省略腋窝处理也可使 RR 降低，大多数病人接受局部放疗。同样，在 ypN1 (ALND) 疾病的病人中，省略 RNI 也可使 5 年 RR 率降低。在少数将 ALND 替换为 RNI 的研究中，发现 ypN1 (SLNB) 疾病的病人 RR 也很低。对于 PST 前淋巴结肿瘤负荷高且 ypN0 (SLNB) 的病人，替换 ALND 为 RNI 也可使 RR 降低。由于病人数量有限，这些数据应谨慎解读。我们得出结论，尽管缺乏一级证据，但在选择的病例中可以考虑 PST 后 RNI 的逐步减少。 版权所有 © 2023 作者。由爱思唯尔（Elsevier）有限公司出版。保留所有权利。

Pathologic complete response (pCR) after Primary Systemic Treatment (PST) for breast cancer is associated with excellent long-term outcomes. With increasing use of PST, the indication for regional nodal irradiation (RNI) has been challenged. The aim of this paper is to review the literature on de-escalation of RNI in patients treated with PST. We found no level 1 evidence on de-escalation of RNI after PST, but several randomized trials are ongoing. Consequently, current de-escalation strategies are based on cohort studies. These studies showed that in patients with low nodal tumour burden (LNTB) (≤3 suspicious nodes at imaging) prior to PST, and ypN0 based on Axillary Lymph Node Dissection (ALND), omission of RNI resulted in very low regional recurrences (RR) without compromising survival. In patients with LNTB and ypN0 based on Sentinel Lymph Node Biopsy (SLNB), omission of axillary treatment also resulted in low RR; the majority of these patients received local radiotherapy. Similarly, in patients with ypN1 (ALND) disease, omission of RNI resulted in low 5-year RR rates. Low RR-rates were also found in the few studies replacing ALND by RNI, in patients with ypN1 (SLNB) disease. In patients with high nodal tumour burden prior to PST and ypN0 (SLNB), replacing ALND by RNI also resulted in low RR. Due to the limited number of patients, these data should be interpreted with caution. We conclude that although level 1 evidence is lacking, de-escalation of RNI after PST can be considered in selected cases.Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.