ESTRO 2025 - Abstract Book

S2052

Clinical - Urology

ESTRO 2025

with image-guided fiducial markers is used to ensure precision. Acute toxicities are assessed using RTOG scoring criteria and patient-reported outcomes (IPSS and IIEF-5) at the end of treatment and at 3-month. Late toxicities are similarly evaluated at 6, 12, and 24-month. Secondary endpoints include biochemical and clinical progression-free survival (bPFS, cPFS) and cancer-specific survival (CSS). Androgen deprivation therapy (ADT) is prescribed as per NCCN guidelines. Results: To date, 34 patients were enrolled, three were excluded due to findings of N1 or T3b disease on pre-treatment mpMRI. So far, 30 patients completed the radiotherapy course, of them 13 received concomitant ADT (6 – 12m). At the end of treatment, GU grade 1 toxicity was observed in 33% of patients while grade 2 symptoms in 10%. GI toxicity occurred in 7%, all grade 1. At 3-month, GU toxicities decreased to 15%, including one grade 2 case (4%) and only one patient (4%) reported grade 2 GI toxicity. At 6-month, late GU toxicity was observed in 11%, including one grade 2 case (5%). GI toxicity was reported in 11%, all grade 1. At 12-month, late GU and GI grade 1 toxicities were recorded in 22% each, with grade 2 toxicity in 11% for GU and 5% for GI. At a median FU of 7.3-month, there were no cases of grade ≥3 toxicity or treatment -related deaths. Median PSA pre-RT 6.29 ng/ml and median PSA at last FU 0.66 ng/ml.

Conclusion: Preliminary data from the PRO-SPEED trial demonstrated that prostate UH-SBRT with SIB to the DIL using CyberKnife® system is a safe and effective treatment, with low rates of GU and GI toxicities and excellent early biochemical and clinical control. These results highlight the feasibility of this regimen, though longer follow-up and analysis of patient-reported toxicities are needed to confirm its long-term efficacy and tolerability.

Keywords: prostate, cyberknife, radiosurgery

References: Mazzola GC, Vincini MG, Rondi E, Ronci G, Vigorito S, Zaffaroni M, Corrao G, Gallo S, Zerini D, Durante S, et al. CyberKnife Ultra-Hypofractionated SBRT for Localized Prostate Cancer with Dose Escalation to the Dominant Intraprostatic Lesion: In Silico Planning Study. Applied Sciences . 2023; 13(12):7273. https://doi.org/10.3390/app13127273