ESTRO 2025 - Abstract Book

S2067

Clinical - Urology

ESTRO 2025

Conclusion: We demonstrate the feasibility of delivering SABR in patients with mainly high risk prostate cancer. 5 year outcomes were good with acceptable clinician and patient reported toxicity. Phase 3 trials are underway.

Keywords: Prostate, SABR, toxicity

References: 1. A Randomized Feasibility Trial of Stereotactic Prostate Radiation Therapy With or Without Elective Nodal Irradiation in High-Risk Localized Prostate Cancer (SPORT Trial). Houlihan, Orla A. et al. International Journal of Radiation Oncology, Biology, Physics, Volume 117, Issue 3, 594 - 609

3800

Digital Poster Ablative Radiotherapy for Unfavorable Prostate Tumors (ABRUPT): 24-month Results of Toxicity and QoL Following Single-Dose Ablative Radiotherapy Chiara Chissotti 1,2 , Federica Ferrario 1,2 , Valeria Faccenda 3 , Riccardo Ray Colciago 2 , Elena De Ponti 3,2 , Denis Panizza 3,2 , Stefano Arcangeli 1,2 1 Department of Radiation Oncology, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy. 2 School of Medicine and Surgery, University of Milan Bicocca, Milan, Italy. 3 Department of Medical Physics, Fondazione IRCCS San Gerardo dei Tintori, Monza, Italy Purpose/Objective: To assess late gastrointestinal (GI) and genitourinary (GU) side effects in patients with organ-confined unfavorable prostate cancer (PCa) treated with single-dose ablative radiotherapy (SDART). Material/Methods: Thirty patients enrolled in a single-arm prospective trial received 24 Gy SDART to the whole prostate with urethra sparing and organ motion control, delivered on a Linac platform with a 10 MV FFF single partial arc. Androgen deprivation therapy (ADT) was prescribed according to standard care. Treatment-related acute and late GU and GI toxicities (CTCAE_v5 scale) and quality-of-life (QoL) outcomes (EORTC QLQ-PR25/C30, IPSS, IIEF5) were assessed at multiple time points. Minimal Important Difference (MID) was defined as a change of >0.5 pooled SD from baseline. Statistical analysis included ANOVA and logistic regression. Results: The median age was 77 years (range, 62 – 84) and the median initial PSA level was 8.0 ng/mL (range, 3.4 – 18.3). Intermediate unfavorable and high-risk PCa accounted for 33% and 67%, respectively. Patient, tumor, and treatment characteristics are summarized in Table 1. Twenty-nine out of 30 patients (97%) received ADT for a median duration of 12 months (range, 6 – 24). After a median follow-up of 24 months (range, 9 – 37), no grade ≥3 late toxicities were observed. Late GU toxicities included 16 (53%) patients with G0, 9 (30%) with G1, and 5 (17%) with G2. Late GI toxicities included 27 (90%) patients with G0, 1 (3%) with G1, and 2 (7%) with G2. Significant QoL changes were observed in PR25 Urinary (median 15, range 0 – 58, P=0.0089) and IIEF-5 (median 7, range 0 – 25, P=0.0221), with 16 and 9 patients showing deterioration, respectively, compared to baseline and 3 months. Conversely, no significant differences were found for IPSS (P=0.5864), QoL (P=0.1935), or PR25 Bowel (P=0.8860). Logistic regression analysis identified that lower baseline PR25 Urinary scores (OR=0.90, P=0.042) and MID QoL at 3 months (OR=6.0, P=0.050) were significantly associated with MID urinary late. Additionally, MID PR25 Bowel at 3 months was significantly associated with MID bowel late (OR=15.33, P=0.046). None of the patients experienced a biochemical failure, with a median PSA of 0.11 ng/mL (range, 0.01 – 0.62).