ESTRO 2025 - Abstract Book

S2112

Clinical - Urology

ESTRO 2025

References: Marvaso, G., Ciardo, D., Corrao, G., Gandini, S., Fodor, C., Zerini, D., ... & Jereczek-Fossa, B. A. (2019). Radioablation+/− hormonotherapy for prostate cancer oligorecurrences (Radiosa trial): potential of imaging and biology (AIRC IG-22159). BMC cancer, 19, 1-7. Zaffaroni, M., Vincini, M.G., Corrao, G., Lorubbio, C., Repetti, I., Mastroleo, F., Putzu, C., Villa, R.,Netti, S., D’Ecclesi is, O., et al. (2023). Investigating Nutritional and Inflammatory Status as PredictiveBiomarkers in Oligoreccurent Prostate Cancer — A RADIOSA Trial Preliminary Analysis. Nutrients,15, 4583.

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Digital Poster Biochemical response after metabolic imaging-guided radiotherapy PSMA-1007 in biochemical recurrence of prostate cancer after radical prostatectomy Francesco Amorelli 1 , Pedro Jose Plaza 2 , Augusto Octavio Natali 3 , Juan Sebastian Blanco 2 , Palmira Foro 1 1 Radiation Oncology, Hospital del Mar, Barcelona, Spain. 2 Nuclear Medicine, Hospital del Mar, Barcelona, Spain. 3 Clinical analyses, Hospital Josep Trueta, Girona, Spain Purpose/Objective: To evaluate the biochemical response (BR) of patients with biochemically-relapsed prostate cancer (PC) after radical prostatectomy (RP) treated with positive PSMA-1007 image-guided radiotherapy. Material/Methods: We prospectively included 62 patients with biochemical-recurrence (BCR) of PC who had undergone RP with PSA levels <0.5ng/mL. Patients were evaluated for salvage radiotherapy (SRT) to prostate-bed (PB) with conventional radiological-imaging (abdominopelvic-CT, bone-scan, and pelvic-MRI) negative. Prior to radiotherapy planning, all patients underwent 18F-PSMA-1007-PET/CT. The results of the scan were categorized as local-recurrence, pelvic/extrapelvic lymph-node (LN), bone/visceral disease. The potential adjustments or changes to radiotherapy planning fields influenced by PSMA-1007- positive findings were analyzed, as well as their impact on patients’ BR, assessed through PSA-levels post-PSMA. Quantitative-variables were described through mean/standard-deviation.Qualitative-variables were described through frequencies-table. Group-comparisons were performed with Chi-square/Fisher-exact, for categorical variables and Mann – Whitney-U for continuous-variables. Optimal-cut-off points were determined using-ROC-curves. Results: We included 62 patients with a mean-age of 68y, initially classified as localized disease with low-risk (3.5%), favorable-intermediate-risk (25.9%), unfavorable-intermediate-risk (34.1%), and high-risk (36.5%). These patients underwent RP and were evaluated for SRT in PB with PSA-values<0.5 ng/mL. Positive-PSMA-1007 results were observed in 64.5% (40/62). Disease-detection-rates were 52.7% for local-recurrence, 34.6% for nodal-disease (pelvic/extrapelvic-LN), 10.9% for bone-metastases, and 1.8% for visceral-metastases. The majority of patients had PSA between 0.20-0.50ng/mL with PSA-doubling-time (DT-PSA) <10months. Analysis of ROC-curves identified PSA values of 0.40ng/mL (AUC 0.60) and DT-PSA of 5.3months (AUC 0.80) as optimal cut-off-points. Post-PSMA-1007 modifications/changes in radiotherapy-plan were made in 100% of the positive results. They were classified as minor/major-changes. Minor-changes were made in 60% of cases included radiotherapy to PB 66Gy (2Gy/Fx) with dose-escalation to 70-72Gy and radiotherapy to pelvic-LN-areas 46Gy (2Gy/Fx) with dose-escalation to pathological-LN to 55Gy. All dose-escalations were guided by positive-PSMA-1007-imaging. Major-changes occurred in 40% of patients (mostly oligometastatic disease), included PSMA-1007 metabolic-volume-guided-SBRT, the most commonly used scheme 24Gy (3/fractions) combined with systemic-therapy with new-generation-antiandrogens and TDA. In patients with negative-PSMA-1007, 66Gy (2Gy/Fx) radiotherapy to PB was performed in 17 patients and watchful-waiting in 5.