S166
Brachytherapy - Urology
ESTRO 2026
1 Radiotherapy, Radiotherapiegroep, Deventer/Arnhem, Netherlands. 2 Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands Purpose/Objective: To compare toxicity patterns of I-125 brachytherapy (BT) and MR-linac ultra-hypofractionated radiotherapy (UHF-RT) for low- and intermediate-risk prostate cancer. At our institute, oncological outcomes, toxicity, and quality of life are prospectively collected, enabling a balanced comparison between both treatments. Material/Methods: Since January 2021, men with low- or intermediate-risk prostate cancer were treated with UHF-RT (36.25 Gy in 5 fractions, 2–3/week) or BT (145 Gy). Prospectively collected data included patient-reported outcomes (PROMS: EPIC-50, IPSS), physician-reported toxicity (CTCAE v5.0), and PSA. Propensity score matching (1:1 nearest neighbour with caliper 0.15) created comparable groups based on age, prostate volume, ISUP grade, T-stage, and baseline PSA. PROMS were analyzed using the Mann–Whitney U test. Results: Data from 719 patients (BT n=296, UHF-RT n=423) were eligible. After matching, two balanced groups remained (n=149 each), with no significant differences in age, prostate volume, ISUP grade, T-stage, or baseline PSA.Genitourinary (GU) EPIC scores were similar at baseline (BT: 95 [IQR 89–100] vs UHF-RT: 95 [IQR 88–100], p=0.75) and declined at three months (BT: 73 [62–87] vs UHF-RT: 91 [81–97], p<0.001). This difference persisted up to two years, although it decreased over time (Figure 1). A similar pattern was observed in IPSS scores: at baseline, BT: median 5 [3– 9] vs UHF-RT: 6 [3–11] (p=0.19), increasing at three months to BT: 13 [8–19] vs UHF-RT: 8 [5–14] (p<0.001) (Figure 2).
Primary outcomes included local control (LC), progression-free survival (PFS), and overall survival (OS). Results: After a median follow-up of 63.5 months (mean 70.4, range 3–231), oncological outcomes were excellent. LC rates were 99.6% at 3 years, 98.8% at 5 years, and 98.4% at 10 years.PFS was 98%, 96.8%, and 96% at 3, 5, and 10 years, respectively. OS reached 98.4% at 5 years and 96% at 10 years.During the 231-month follow-up, 8.4% of patients developed biochemical recurrence, whereas in-field progression was observed in only 1.6%. Patients receiving ADT achieved 100% LC across all timepoints. Patterns of failure were predominantly distant (lymph nodes and bone). Conclusion: The combination of EBRT and HDR brachytherapy boost yields outstanding long-term LC, PFS, and OS for intermediate- and high-risk prostate cancer, confirming this regimen as a highly effective treatment strategy. The dominant pattern of failure was distant, underscoring the need for optimized systemic therapy integration in high-risk patients.Keywords: Prostate cancer, High-dose-rate brachytherapy, External beam radiotherapy, Dose escalation, Local control, Progression-free survival, Androgen deprivation therapy Keywords: Prostate Cancer References: Sung H CA Cancer J Clin 2021;71:209. Dearnaley D Lancet Oncol 2016;17:1047. Kuban DA IJROBP 2008;70:67. Zietman AL JCO 2010;28:1106. Michalski JM JAMA Oncol 2018;4:e180039. Hoskin PJ Radiother Oncol 2012;103:217. Mendez LC TAU 2018;7:357. Moll M Strahlenther Onkol 2025;201:11. Miszczyk M Radiother Oncol 2023;183:109632. Aizawa R IJCO 2025;30:1448. Onal C RPOR 2024;29:10. Nag S IJROBP 1999;44:789. Kovács G Radiother Oncol 2005;74:137. Yamada Y Brachytherapy 2012;11:20. Morris WJ IJROBP 2017;98:275. Spratt DE BJU Int 2014;114:360. Pisansky TM JCO 2015;33:332. Bolla M Lancet 2002;360:103. Jursinic P JACMP 2014;15:4586. Soror T Cancers 2021;13:912. Hofman MS Lancet 2020;395:1208. Henry A Radiother Oncol 2022;167:244.
Digital Poster Highlight 1861
Higher patient-reported urinary toxicity after I-125 brachytherapy vs MR-linac ultra-hypofractionation in low–intermediate risk prostate cancer Marinus T Jutten 1 , Tonnis T Nuver 1 , Marnix J A Rasing 1,2 , Wout J Schoevers 1 , Marie A D Haverkort 1 , Michal D Czerwinski 1 , Erik C Schimmel 1 , Paul M Jeene 1 , Laura S Hermens 1 , Danny Schuring 1 , André W Minken 1 , Max Peters 1,2
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