The Reirradiation Collaborative Group (ReCOG) surveyed 37 breast radiation specialists across Europe and North America to characterize contemporary practice patterns. While IMRT/VMAT emerged as the dominant technique and most reported summating prior radiation plans when available, there was little to no consensus on what was being evaluated or optimized. Reported cumulative dose constraints for critical structures showed striking variability, reflecting major variation in how clinicians account for prior radiation and tissue recovery. The brachial plexus was the most frequently constrained structure, with reported cumulative maximum doses ranging from 51–85 Gy. Common reasons to avoid re-irradiation were significant prior toxicity (e.g., fibrosis or lymphedema) and short disease-free interval. Dose-fractionation schedules ranged from 40 Gy in 15 fractions to 60 Gy in 30 fractions, with only a minority employing twice-daily regimens. Ultimately, prospective reirradiation registries remain a high priority for achieving clarity. | Hong, Pract Radiat Oncol 2026
