In this study, the locations of local recurrences after radical prostatectomy were mapped using a cohort of >1000 patients who had Ga98-PSMA PET scans. There were 140 sites of local recurrence among 132 positive PET scans that were mapped according to distance above and below the vesicourethral anastomosis (VUA) and within or without the RTOG prostate fossa CTV. Overall, 98.6% of recurrences fell within the RTOG consensus CTV. The most frequent recurrence location was within 5 mm above and below the VUA (22%), however recurrences were fairly evenly distributed with the most superior and inferior recurrences 6.1cm above and 1.4cm below the VUA, respectively. Important takeaways were 1) the only recurrences outside the RTOG CTV were below the standard margin, 2) only 1 recurrence was located in the anterior CTV margin >1.5cm from the posterior bladder wall, and 3) a substantial proportion (45%) were located in the midline and posterolateral recess of the upper CTV (>2.5cm above the VUA).
- Horsley, Int J Radiat Oncol Biol Phys 2022