ESTRO 2025 - Abstract Book

S2025

Clinical - Urology

ESTRO 2025

approach was proposed. Changes to the original-intent were evaluated based on positive/negative PET/CT-PSMA results.

Results: We included 85 patients (mean-age 69y). Initial staging T2 (50.58%)-T3 (48.23%), N1 (4.7%), Gleason<8 (56.4%) and >8 (43.52%). All underwent RP, 14.11% received ART, 38.82% SRT, and 38.82% ADT. Positive PET/CT-PSMA results were seen in 53% (45/85) of patients. The median-PSA level before scanning was 0.59ng/mL, and the median PSA-DT was 7months. 90 lesions were identified (21 PB, 48 pathological-LN, 18 bone-lesions and 3 visceral-lesions) undetected by conventional imaging(figure1). ROC-analysis identified a PSA of 0.55ng/mL (AUC 0.72) and PSA-DT cut-off of 9months (AUC 0.60) as the optimal cut-off-values for predicting positive PET/CT-PSMA results. Post-PSMA changes in treatment were observed in 84.4% of positive results (p<0.001). The most key-changes included PSMA-guided-SBRT for 50% of cases targeting pelvic-LN or oligometastatic lesions, often combined with ARSI’s (29%). Other recommendations included pelvic -radiotherapy (PRT) in 23.6%, and dose-escalated PBRT for PSMA-positive areas 10.5%(figure2). The most used radiotherapy schedules were 24Gy in 3/fractions for SBRT, 45 46Gy in PRT (dose-escalation 55Gy for pathological-LN). 66Gy in PB with dose-escalation to 70 – 72Gy in PSMA positive areas. For negative PET/CT-PSMA, 41% with no prior radiotherapy received PBRT, while 59% followed a watchful-waiting approach. Post-treatment changes median-PSA level was 0.08ng/mL(p<0.001).