DEGRO practical guidelines: radiotherapy of breast cancer—regional nodal irradiation

AIM: The aim of this work is to update the practical guidelines for adjuvant radiotherapy of the regional lymphatics in breast cancer, originally issued in 2014 by the Breast Cancer Expert Panel of the German Society of Radiation Oncology. METHODS: A comprehensive literature review concerning regional nodal irradiation (RNI) was performed using the search terms "breast cancer," "radiotherapy," and "regional node irradiation." Furthermore, data from recently published meta-analyses and international breast cancer society guidelines-providing new insights since 2014-served as the basis for defining evidence-based recommendations. This paper delineates the indications and dose-fractionation strategies for radiotherapy targeting the regional lymphatic pathways following breast cancer surgery. RESULTS: The guideline was updated to reflect current evidence regarding radiotherapy of the lymphatic drainage system. The recommendations are categorized according to two primary objectives for RNI: (1) improving oncological outcomes; (2) enabling de-escalation of axillary surgery. The update distinguishes between clinical scenarios with and without neoadjuvant chemotherapy (NACT). Specifically, it addresses the increasingly relevant topic of treatment de-escalation following pathologic complete response (pCR) after NACT in initially node-positive patients. CONCLUSION: The updated guidelines address current developments and ongoing challenges in RNI. They provide clinically oriented recommendations for establishing indications in both the primary (upfront) surgery setting and following neoadjuvant therapy.