Shadows and Light: The Evolution of Postmastectomy Radiation Therapy and Regional Nodal Irradiation in the Era of De-Escalation.

Radiation therapy represents a cornerstone in the management of breast cancer, from early-stage to advanced cancers. For appropriately selected patients, postmastectomy radiation therapy (PMRT) and regional nodal irradiation (RNI) have historically been shown to improve locoregional control and survival. However, PMRT is associated with an increased risk of cardiopulmonary toxicity, lymphedema, and reconstruction complications. This has led clinicians to re-evaluate a one-size-fits-all approach to PMRT and RNI, instead, looking for a more refined approach to maximizing the therapeutic ratio. This review explores the historical foundations, landmark trials, and paradigm-shifting updates that have transformed PMRT and RNI from broad, uniform strategies into nuanced, patient-specific therapies. Emphasis is placed on the evolution of patient selection, advances in fractionation, and the integration of new approaches. This is a story of progress, precision, and the pursuit of balance in the management of patients with breast cancer.