S1164
Clinical - Urology
ESTRO 2026
early biochemical response, its influence on sustained remission remains unclear. References: Borzillo V, Scipilliti E, Pezzulla D, Serra M, Ametrano G, Quarto G, Perdonà S, Rossetti S, Pignata S, Crispo A, Di Gennaro P, D'Alesio V, Arrichiello C, Buonanno F, Mercogliano S, Russo A, Tufano A, Di Franco R, Muto P. Stereotactic body radiotherapy with CyberKnife® System for low- and intermediate-risk prostate cancer: clinical outcomes and toxicities of CyPro Trial. Front Oncol. 2023 Nov 7;13:1270498. doi: 10.3389/fonc.2023.1270498. PMID: 38023175; PMCID: PMC10660677. Keywords: Cyberknife Radiosurgery Prostate Digital Poster 1012 DVH-based analysis of genitourinary side effects in robotic SBRT prostate treatments David Sevillano 1 , Isabel Alvira 2 , Mª Dolores Espinosa 2 , Asunción Hervás 2 , Jose Antonio Domínguez-Rullán 2 , Juan David García-Fuentes 1 , Fernando López 2 , Carmen Vallejo 2 , Miguel Cámara 1 , Rafael Morís 1 , Rafael Colmenares 1 , Belén Capuz 1 , Carlos Rodríguez- Manzaneque 1 , Juan Trujillo 1 , Iago Millán 1 , María José Béjar 1 , Daniel Prieto 1 , Sonsoles Sancho 2 , Feliciano García-Vicente 1 1 Medical Physics, H. U. Ramón y Cajal, IRYCIS, Madrid, Spain. 2 Radiation Oncology, H. U. Ramón y Cajal, IRYCIS, Madrid, Spain Purpose/Objective: To find correlation between DVH parameters and GU side effects in prostate SBRT treatments at our institution Material/Methods: 162 intermediate-risk prostate cancer patients treated with robotic SBRT were included in this study. Median follow-up was 22.8 months. Both acute and chronic GU side effects were evaluated. Dose prescription was 36.25 Gy in 5 fractions. DVHs of rectum, bladder, urethra, urethra PRV (n=111), PTV, prostate and seminal vesicle were obtained from each plan. Dose levels included in the analysis ranged from 0Gy to 30Gy in 5Gy intervals and from 30Gy to 45Gy in 1Gy intervals. Thus, 33 dose levels were analyzed for both absolute and relative DVHs. Dose constraints used for planning were also evaluated. PTV, CTV and OARs volumes, as well as the volume intersecting the PTV with the Rectum and Bladder were included in the analysis.For each variable, logistic regression fits were performed. A result was set as significant if p<0.05. Results: Acute and chronic GU side effects were observed in 57.2% and 25.8% of the patients respectively. Most of them were G1 (acute: 54%, chronic: 25.8%). Due to the
prostate cancer risk stratification models. Physics and imaging in radiation oncology, [online] 34, p.100787. doi:https://doi.org/10.1016/j.phro.2025.100787. Keywords: PSA dynamics, SBRT, Prostate
Digital Poster 1000 Cyberknife Radiosurgery of Prostate Cancer – Results for 200 Patients Sebastian Exner, Felix Behrens, Fabian Fehlauer Cyberknife Center, Strahlenzentrum Hamburg, Hamburg, Germany Purpose/Objective: This study aimed to analyze both the safety profile and therapeutic efficacy of stereotactic ablative radiotherapy (SABR) in patients with low and intermediate risk prostate cancer (PCP) treated at the Strahlenzentrum Hamburg. In addition, the influence of risk classification on oncological outcomes, as well as the effect of androgen deprivation therapy (ADT) and post-treatment PSA kinetics, were examined. Material/Methods: From February 2021 to June 2025, 200 men diagnosed with localized prostate cancer (108 low risk (LR), 92 intermediate risk (IR) including T2c) underwent image- guided SABR using the CyberKnife system. A total dose of 36.25 Gy was administered in five fractions of 7.25 Gy each. At treatment initiation, 58% of patients were on ADT, which was gradually discontinued in all cases by month 30 of follow-up. The median observation time was 18 months. Clinical assessments were performed immediately after therapy, at 3 and 6 months, and then every 6 months. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities were graded according to EORTC/RTOG criteria, alongside regular PSA monitoring. Results: Five patients (2.5%) experienced disease recurrence— three biochemical relapses and two nodal failures. Among these, three were in the LR and two in the IR group. No grade 3 or 4 late toxicities were reported. Acute grade 3 GU and GI reactions occurred in only 0.5% of cases each and resolved within weeks. Most adverse effects were mild (grade 1–2) and transient. Differences in local control or biochemical relapse-free survival between LR and IR groups were not statistically significant. Conclusion: SABR for localized prostate cancer at the Strahlenzentrum Hamburg achieved high treatment efficacy with a very low rate of severe adverse events. The inclusion of T2c cases and the low relapse frequency among intermediate risk patients support the suitability of SABR for selected, more advanced localized stages. While ADT appears to enhance the
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