S1184
Clinical - Urology
ESTRO 2026
Giuseppe Fornarini 13 , Giuseppe C Iorio 14 , Alessia Guarneri 15 , Michele Sisani 16 , Veronica Mollica 17 , Alfio Di Grazia 18 , Cinzia Ortega 19 , Alessia Reali 20 , Mattia F Osti 21 , Lorenzo Livi 1 1 Radiation Oncology Unit, Oncology Department, Azienda Ospedaliero Universitaria Careggi, Florence, Italy. 2 Cancer Risk Factors and Lifestyle Epidemiology Unit,, Institute for Cancer Research, Prevention and Clinical Network (ISPO), Florence, Italy. 3 Radiation Oncology Unit, Department of Oncology and Hematology, University Hospital of Modena, Modena, Italy. 4 Radiotherapy Unit, Azienda Ospedaliera Universitaria, Parma, Italy. 5 Unit of Radiotherapy, Azienda USL-IRCCS di Reggio Emilia, Reggio Emilia, Italy. 6 Department of Oncology,, Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Rome, Italy. 7 UOC di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy. 8 Department of Oncology, Fondazione Policlinico Universitario Agostino Gemelli, Rome, Italy. 9 Medical Oncology Unit, Macerata Hospital, Macerata, Italy. 10 Radiation Oncology Section, Department of Medicine and Surgery, University of Perugia, Perugia, Italy. 11 Department of Oncological Urology, Veneto Institute of Oncology IOV-IRCCS, Padua, Italy. 12 Radiation Oncology Unit, Department of Oncology, "Santa Maria della Misericordia" University Hospital, Azienda Sanitaria Universitaria Friuli Centrale, Udine, Italy. 13 Medical Oncology Unit 1, IRCCS Ospedale Policlinico San Martino, Genoa, Italy. 14 Department of Oncology, Radiation Oncology, University of Turin, Turin, Italy. 15 Department of Radiation Oncology, Candiolo Cancer Institute, FPO- IRCCS, Turin, Italy. 16 Medical Oncology, Usl Toscana Sud est, Arezzo, Italy. 17 Medical Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy. 18 Radioterapia Humanitas, Istituto Clinico Catanese, Catania, Italy. 19 Medical Oncology, Michele and Pietro Ferrero Hospital, Verduno, Italy. 20 Radiation Oncology Department, Michele and Pietro Ferrero Hospital, Verduno, Italy. 21 UOC Radioterapia, Azienda Ospedaliero-Universitaria Policlinico Sant'Andrea, Sapienza, Università di Roma, Rome, Italy
Material/Methods: Patients with metachronous oligometastatic HSPC ( ≤ 5 non-visceral metastases on conventional imaging) were randomized to receive either apalutamide plus ADT (Arm A, control) or the same systemic therapy combined with SBRT to all visible metastatic sites (Arm B, experimental). Patients with de novo metastatic disease or >5 lesions were excluded. Here we present results focusing on biochemical response (BR) defined as PSA reduction > 50% if compared to baseline, and complete biochemical response (CBR), defined as PSA <0.2 ng/mL at 6 months after treatment start. Results: A total of 174 patients were enrolled. At 6 months, BR was detected in 96.6 and 98.8% of patients in Arm A and ARM B, respectively (OR 3, 95%CI 0.31-29.42, p=0.46). CBR was achieved in 93.2% of patients in Arm A and 96.5% in Arm B (OR 2.02, 95% CI 0.49–8.37, p=0.33). These findings were consistent across subgroups defined by lesion count (1–2 vs 3–5) and presence of PSMA-positive lesions not detected on conventional imaging. Notably, patients with <3 lesions had significantly higher CBR rates at 6 months if compared to patients with 3-5 lesions (99.3% vs 91.2%, respectively, p=0.07) independent of treatment arm. Conclusion: In this population, high rates of BR and CBR at 6 months were reported in both arms of treatment. The addition of SBRT to apalutamide plus ADT did not significantly improve CBR at 6 months. However, a lower metastatic burden (<3 lesions) was associated with higher CBR rates, suggesting a prognostic role of disease extent. Longer follow up is needed to assess the impact of SBRT on progression-free and overall survival. References: Francolini G, Allegra AG, Detti B, Di Cataldo V, Caini S, Bruni A, Ingrosso G, D'Angelillo RM, Alitto AR, Augugliaro M, Triggiani L, Parisi S, Facchini G, Banini M, Simontacchi G, Desideri I, Meattini I, Valicenti RK, Livi L; ARTO Working Group members. Stereotactic Body Radiation Therapy and Abiraterone Acetate for Patients Affected by Oligometastatic Castrate- Resistant Prostate Cancer: A Randomized Phase II Trial (ARTO). J Clin Oncol. 2023 Dec 20;41(36):5561-5568. Keywords: Hormone sensitive, Prostate Cancer, SBRT
Purpose/Objective: Apalutamide in combination with androgen
deprivation therapy (ADT) is an established standard of care for metastatic hormone-sensitive prostate cancer (mHSPC). In the castration-resistant setting, the addition of stereotactic body radiotherapy (SBRT) to first-line androgen receptor pathway inhibitors (ARPIs) has demonstrated improved radiological progression- free survival. The PERSIAN trial (NCT05717660) is a randomized phase II study evaluating the benefit of combining SBRT with ARPIs in the mHSPC setting.
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Predictive value of prostate volume and baseline urinary function across three SBRT fractionation regimens Valeria Faccenda 1,2 , Federica Ferrario 3 , Lorenzo De Sanctis 2 , Giulia Rossano 2 , Riccardo Ray Colciago 2 , Elena De Ponti 1,2 , Stefano Arcangeli 2,3
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