ESTRO 2022 - Abstract Book

S531

Abstract book

ESTRO 2022

G. Francolini 1 , B. Detti 1 , V. Di Cataldo 2 , S. Caini 3 , A.R. Alitto 4 , S. Parisi 5 , C. Demofonti 6 , A. Bruni 7 , G. Ingrosso 8 , G. Timon 9 , A. Tagliagambe 10 , M. Aquilano 11 , L.P. Ciccone 11 , V. Salvestrini 11 , G. Frosini 11 , C. Cerbai 11 , A. Allegra 11 , L. Burchini 12 , I. Desideri 13 , M. Mangoni 14 , I. Meattini 14 , L. Livi 14 1 Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit Oncology Department, Florence, Italy; 2 Istituto Fiorentino di Cura e Assistenza (IFCA), Radiation Oncology CyberKnife Center, Florence, Italy; 3 Institute for Cancer Research, Prevention and Clinical Network (ISPRO), Cancer Risk Factors and Lifestyle Epidemiology Unit, Florence, Italy; 4 Fondazione Policlinico Universitario A. Gemelli IRCCS, U.O.C. di Radioterapia Oncologica, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Rome, Italy; 5 University of Messina, Department of Biomedical and Dental Sciences and Morpho-Functional Imaging, Messina, Italy; 6 Tor Vergata General Hospital, Radiotherapy Unit, Department of Oncology and Hematology, Rome, Italy; 7 University Hospital of Modena, Radiation Therapy Unit, Department of Oncology and Hematology, Modena, Italy; 8 University of Perugia, Radiation Oncology Section, Department of Surgical and Biomedical Science, Perugia, Italy; 9 AUSL-IRCCS di Reggio Emilia, Radiation Oncology Unit, Clinical Cancer Centre, Reggio Emilia, Italy; 10 Azienda Azienda Usl 1 di Massa e Carrara, Struttura Complessa UO Radioterapia, Massa Carrara, Italy; 11 University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Florence, Italy; 12 University of Florence, Department of Biomedical, Experiemental and Clinical Sciences "Mario Serio", Florence, Italy; 13 University of Florence, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Florence, Italy; 14 University of Florence - Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", Azienda Ospedaliero Universitaria Careggi - Radiation Oncology Unit Oncology Department, Florence, Italy Purpose or Objective A multicentre, randomized trial testing the benefit of stereotactic body radiation therapy (SBRT) addition to abiraterone acetate (AA) in oligometastatic Castrate Resistant Prostate Cancer (CRPC) patients (ARTO, NCT03449719) is currently running in 16 Italian centres. Here we present an early report, exploring efficacy results of SBRT+AA combination after enrollment of 79% of target sample. Materials and Methods Patients affected by oligometastatic CRPC (<3 non-visceral metastatic lesions) were enrolled in the trial. Patients were randomized 1:1 to receive either AA alone (control arm) or associated with concomitant SBRT on all sites of disease (treatment arm). Primary endpoint is biochemical response, defined as a PSA ≥ 50% from baseline measured within 6 months from treatment start (BR). PSA drop (PSA reduction at 6 months if compared to baseline, expressed as a logarithmic function, logPSA) and complete biochemical response (CBR), defined as PSA at 6 months ≤ 0.2 ng/ml are secondary endpoints of the trial. All included patients had ≥ 6 months of follow up. Results One hundred twenty-three patients were enrolled in ARTO trial, 98 patients were evaluable for this analysis. 76.5% of patients had BR (82.2% vs. 71.7% in treatment vs. control arm, respectively), with an unadjusted odds ratio (OR) of 1.83 (95%CI 0.69-4.82, p-value 0.22). After adjustment for baseline PSA and metastatic sites (>1 vs. 1), the OR for BR was 2.23 (95%CI 0.74-6.73, p-value 0.15). A nearly significant trend for a lower logPSA at 6 months was detected in treatment vs control arm (beta -0.76, 95%CI -1.58, 0.05, p-value 0.064). 36.7% of patients had CBR (46.7% vs. 28.3% in treatment vs. control arm, respectively) with an unadjusted OR equal to 2.22 (95%CI 0.96-5.12, p-value 0.06), and an adjusted OR equal to 2.31 (95%CI 0.90-5.92, p-value 0.08). Baseline PSA and >1 metastatic sites were non-significantly associated with CBR in multivariable models, with OR equal to 0.92 (95%CI 0.85-1.01, p-value 0.06) and 1.20 (95%CI 0.46-3.09, p-value 0.71), respectively. Conclusion Promising efficacy of SBR+AA combination was shown if compared to standard of care alone for oligometastatic CRPC. Even if statistical significance is not yet reached, treatment arm resulted in OR for BR and CBR doubled if compared to control arm. Moreover, PSA drop confirmed this trend. Selection criteria may be further refined, considering that baseline burden of disease was suggested to predict increased outcomes after SBRT. Whole cohort will be enrolled in 2022, final results for primary endpoint may confirm early outcomes in a larger population. V. Murthy 1 , S. Chilukuri 2 , I. Mallick 3 , P. Maitre 4 , A. Agarwal 5 , A.S. Moses 6 , F. James 7 , K. Narang 8 , T. Kataria 8 , A. Anand 9 , D.N. Dutta 10 , S. Mitra 11 , S. Pavamani 12 , S. Mallick 13 , N. Mahale 14 , M. Chandra 15 , A. Narayan 16 , T. Shahid 17 , M. Sairam 18 , V. Kannan 19 , S. Mohanty 20 , T. Basu 21 , C. Hotwani 22 , B. G 23 1 Tata Memorial Centre, Radiation Oncology, Mumbai, India; 2 Apollo Proton Cancer Centre, Radiation Oncology, Chennai, India; 3 Tata Medical Centre, Radiation Oncology, Kolkata, India; 4 Tata Memorial Centre, Radiation Oncology, Kolkata, India; 5 Tata Memorial Centre, Radiation oncology, Mumbai, India; 6 Tata medical centre, Radiation oncology, Kolkata, India; 7 RCC, Raiation Oncology, Trivandrim, India; 8 Medanta, Radiation oncology, Gurugram, India; 9 Max Hospital, Radiation Oncology, Delhi, India; 10 Amrita Institute of Medical Sciences, Radiation oncology, Kochi, India; 11 Rajiv Gandhi Cancer Institute, Radiation oncology, New Delhi, India; 12 CMC, Radiation oncology, Vellore, India; 13 Narayan Super speciality hospital, Radiation oncology, Howrah, India; 14 Nirali Memorial Radiation Centre and Bharat Cancer Hospital, Radiation oncology, Surat, India; 15 Jupiter Hospital, Radiation oncology, Thane, India; 16 GKNM Hospital, Radiation oncology, Coimbatore, India; 17 Apollo Gleneagles Hospital, Radiation oncology, Kolkata, India; 18 Kovai Medical Centre, Radiation oncology, Coimbatore, India; 19 Hinduja Hospital, Radiation oncology, Mumbai, India; 20 Sterling Cancer Hospital, Radiation oncology, Rajkot, India; 21 HCG Cancer Centre, Radiation oncology, Mumbai, India; 22 Alexis Multispeciality Hospital, Radiation oncology, Nagpur, India; 23 Yashoda Cancer Institute, Radiation oncology, Hyderabad, India Proffered Papers: Urology OC-0606 Multi-institutional outcomes of Gleason grade group 5 prostate cancers treated with EBRT and ADT