Here is the first MRI-based 3D atlas of prostate bed recurrence based on 131 patients harboring 140 local failures after radical prostatectomy. Most recurrences clustered at the vesicourethral anastomosis (53%), followed by the bladder neck (29%) and retrovesical space (18%). Seven commonly used prostate fossa CTV guidelines were then tested against this atlas. EORTC consistently undercovered recurrences, particularly for the dominant VUA failures, largely owing to its more restrictive caudal extent (1.5 cm above penile bulb versus approaching penile bulb with others). While rectal sparing was largely comparable across guidelines, bladder inclusion varied substantially, with EORTC volumes. | Bottero, Pract Radiat Oncol 2026
