RESUMEN
Adjuvant radiotherapy is a key treatment in early-stage breast cancer. The meta-analysis by the Early Breast Cancer Trialist's Collaborative Group (EBCTCG) has demonstrated a decreased risk of locoregional relapse and death after whole-breast radiotherapy. Prophylactic lymph nodes irradiation in breast cancer has also proven to be beneficial in several therapeutic trials. At a time when three-dimensional conformal radiotherapy has become the standard procedure and with the development of intensity-modulated radiation therapy, defining nodal volumes is essential and practices should be harmonized to assess and compare the efficiency and toxicity of radiotherapy. Furthermore, the indication of lymph nodes irradiation has to take into account the risk/benefit balance as expanding the irradiated volume can increase radio-induced toxicity. Selection of patients receiving this treatment is essential. The aim of this update is to define nodal volumes, to precise the indications of their irradiation and to present the expected benefits as well as the potential side effects.