ESTRO 2025 - Abstract Book

S389

Brachytherapy - Urology

ESTRO 2025

D10% 9.3Gy (6.9, 11.6), and rectal V80% 0mL (0, 0). One patient (1.7%) required temporary urinary catheterization. There was only 1 grade 3-5 toxicity, a late grade 3 GU toxicity. Mean IPSS between baseline and 1.5- to 36-months was not significant (p=0.48). Three-year PSA progression-free survival and freedom from ADT rate was 54% and 82%, respectively. Of the 55 patients who had a post-HDR MRI (median 464 days), 46 (84%) patients had a complete response and 9 had persistent disease in the TV. 8 (15%) patients recurred elsewhere in the prostate. Conclusion: Our toxicity, IPSS and PSA failure-free results suggests that focal gland salvage HDR brachytherapy is well tolerated and effective.

Keywords: salvage brachytherapy, prostate cancer

3306

Poster Discussion Focal salvage brachytherapy in previously irradiated patients with locally recurrent prostate cancer Julie Lippens 1 , Louise Willems 1 , Valérie Fonteyne 2 , Tom Vercauteren 2 , Charles Van Praet 3 , Nicolaas Lumen 3 , Camille Berquin 3 , Raju Prasad Srivastava 2 , Geert Pittomvils 2 , Evert J. Van Limbergen 4 , Ludy C.H.W. Lutgens 4 , Robert R.M. Voncken 4 , Ben G.L. Vanneste 2,4 1 Faculty of Medicine and Health Care, Ghent University Hospital and Ghent University, Ghent, Belgium. 2 Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium. 3 Department of Urology, Ghent University Hospital, Ghent, Belgium. 4 Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, Netherlands Purpose/Objective: Despite enhanced outcomes and decreased toxicity in prostate cancer (PC) EBRT 1 , biochemical failure ultimately occurs in 10-40%, with up to 50% of these being solely local 2-4 . However, only <2% of eligible men receives a local salvage therapy 5 . Treating locally recurrent PC post-irradiation is challenging due to nearby organs at risk (OAR), mainly rectum and urethra 6,7 . Brachytherapy (BT) is one of the most compelling salvage RT modalities due to its rapid dose fall-off, which is ideal for re-irradiation settings 6,8 . This study aims to assess dosimetry, PSA evolution, and acute and late toxicity in salvage LDR/HDR BT. Material/Methods: This two-centered observational study includes 61 patients with locally recurrent PC following previous irradiation, who received salvage BT (23% with ADT) between April 2016 and June 2024. All patients underwent PSMA-PET/CT and MRI to exclude metastases. During follow-up, PSA and treatment-related toxicity (CTCAE v5.0) were evaluated. Results: Median (range) age, follow-up, and baseline presalvage PSA were 73 years (58-85), 12 months (1-54), and 4,12 ng/mL (1,1-22,7), respectively. Initial tumor Recurrence

42,9% LDR 145Gy 37,1% HDR 3x10Gy 17,1% HDR 2x13Gy 2,9% HDR 2x10Gy 30,8% LDR 145Gy 42,3% HDR 3x10Gy 23,1% HDR 2x13Gy 3,8% HDR 2x15Gy

57,4% EBRT (median dose 72Gy)

42,6% LDR 145Gy