S1171
Clinical - Urology
ESTRO 2026
References: 1 Ferrario F, Franzese C, Vukcaj S, Faccenda V, Lucchini R, Chissotti C, Colciago RR, Raggi E, Muni R, Di Cristina L, De Sanctis L, Rossano G, Andreoli S, Parabicoli S, Poli GL, Crespi M, Panizza D, Roscigno M, Da Pozzo LF, Magli A, Portaluri M, Scorsetti M, Arcangeli S. Predictors of toxicities and oncological outcomes following postoperative ablative radiotherapy (POPART) for biochemical recurrence. Radiother Oncol. 2025 Oct;211:111072. doi: 10.1016/j.radonc.2025.111072. Epub 2025 Aug 5. PMID: 40759283. Keywords: salvage SBRT, ENI, biochemical recurrence Redefining PSA kinetics after prostate cancer radiotherapy: The prognostic significance of PSA bounces Mariana Borras-Osorio 1 , Federico Mastroleo 1,2 , Mohammad Javad Namazi 1 , Dalton Griner 1 , Bryce Comstock 1 , Aaron Bogan 1 , Lydia Ekama 1 , Brian Davis 1 , Brad Stish 1 , Richard Choo 1 , Ryan Phillips 1 , Thomas Pisansky 1 , William Wong 3 , Andrew Foong 1 , Mi Zhou 1 , David Routman 1 , Mark Waddle 1 1 Department of Radiation Oncology, Mayo Clinic, Rochester, USA. 2 Division of Radiation Oncology, IEO, European Institute of Oncology, IRCCS, Milan, Italy. 3 Department of Radiation Oncology, Mayo Clinic, Scottsdale, USA Digital Poster Highlight 1148 Purpose/Objective: Phoenix criteria remain the standard definition of biochemical recurrence (BCR) after definitive radiotherapy for prostate cancer (PCa).However, recent studies have demonstrated that Phoenix threshold delays recurrence detection in a proportion of patients.1,2 PSA bounce is a phenomenon that further complicates follow-up. This study aimed to characterize PSA bounce in longitudinal post- radiotherapy PSA kinetics and explore its prognostic impact on cancer outcomes. Material/Methods: This retrospective single-institution cohort study included patients with biopsy- proven PCa, treated withdefinitiveradiotherapy between January 2000 and June 2022, minimum 36- month follow-up, and a post-treatment PSA increase with an absolute value >1 ng/dL. Elective nodal
was 0.31ng/mL (range 0.1–0.55). Six patients had Gleason 9(4+5), nine had pT3a/T3b disease, and eight had positive surgical margins. Acute SE were evaluated at three different time points (Table 2) and compared with the overall POPART population (Table 3). No G ≥ 3 events were observed. A slightly higher rate of GI SE was recorded compared with the POPART cohort; however, GI SE improved consistently across the three time points. The number of patients experiencing a MCID in acute is summarized in Table 1 and compared with the POPART population. The patient who experienced a MCID in QoL, sexual function, and IIEF-5 score was the same individual across all domains. Among the three patients with a hormonal MCID, only one had received ADT. Despite the observed higher GI SE, no MCID was detected in the Bowel domain, indicating no clinically significant impact on patients’ QoL.
Conclusion: Although a higher rate of GI SE was observed, ENI delivered with SBRT remains a feasible and well- tolerated option for patients with unfavorable pathological features. This approach may represent a reasonable treatment strategy for high-risk post- prostatectomy patients. Further follow-up and prospective validation are warranted.
irradiation and androgen deprivation therapy (ADT) were allowed. Exclusion
criteriaincludedmetastatic disease at diagnosis, palliative treatment, prior prostatectomy, and incomplete data.Demographic, clinical, and treatment data were collected. PSA increases were classified as bounce ( ≥ 0.2 ng/ml increase followed by a decline
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