Regional Nodal Irradiation

Regional nodal irradiation (RNI) as part of adjuvant radiation therapy represents a standard of care approach in the management of node-positive breast cancer; however, the role of RNI has evolved over the past decade. In clinically node-negative patients found to have nodal involvement on sentinel lymph node biopsy, RNI can be considered in lieu of axillary lymph node dissection (ALND), with reduced rates of lymphedema noted and can be used with breast conservation or mastectomy. In patients undergoing ALND with nodal involvement, RNI is recommended in cases with four or more nodes involved or gross extracapsular extension. In patients with 1–3 nodes involved after ALND, RNI should be considered, with growing data supporting that RNI reduces rates of locoregional recurrence and improves survival coupled with low rates of long-term toxicity. The role of internal mammary radiation continues to be controversial with utilization based on tumor location, the presence of axillary nodal involvement, and the ability to meet cardiopulmonary constraints.