ESTRO 2023 - Abstract Book

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ESTRO 2023

15cc(21.4%), 0-10cc(12.3%) and >20cc(9.1%). Treatment was completed within 17 days for 66 pts, in >17 days for 121 pts. Acute RTOG GU G2+ events were observed in 23% of pts, peaking at the last fr(19.8%, 37 pts). 3 pts experiencing G2+ during the first 6 frs had 80cc resulted a statistically significant predictor(p=0.018), ADT a statistically significant protective factor (p<0.001), and the OTT>17 days a borderline significant protective factor (p=0.05; fig.1B).When employing continuous values for prostate volume cc, bladder V37Gy cc, and IPSS scores, ADT was significantly protective(p=0.001),while greater prostate volumes and higher IPSS scores resulted as significant predictors(p=0.01 and p=0.02, respectively)(fig.1C).RTOG GI G2+ rate at RT end was 2.1%, 1.07% at 1-mo, while no G2+ was recorded at 3-mos.

Conclusion extreme hypofractionation was well tolerated, with acute GU G2+ toxicity peaking at RT end and almost disappearing at 3-mos. Larger prostates and high IPSS scores resulted as GU G2+ predictors, while ADT as the main protective factor. GI G2+ was negligible.

PO-1497 MRgSBRT reirradiation in locally recurrent prostate cancer: a multicentric retrospective analysis

A. D'Aviero 1 , L. Boldrini 2,3 , A. Romano 2 , G. Chiloiro 2 , S. Corradini 4 , V. De Luca 2 , V. Verusio 5 , A. Castelluccia 6 , A.R. Alitto 2 , F. Catucci 1 , G. Grimaldi 6 , C. Trapp 7 , J. Hörner-Rieber 8 , D. Marchesano 6 , V. Frascino 2 , G.C. Mattiucci 1,5 , V. Valentini 2,5 , P. Gentile 6 , M.A. Gambacorta 2,5 1 Mater Olbia Hospital, Radiation Oncology, Olbia, Italy; 2 Fondazione Policlinico Universitario Agostino Gemelli IRCCS, UOC Radioterapia Oncologica, Roma, Italy; 3 Università Cattolica del Sacro Cuore, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, , Roma, Italy; 4 University Hospital LMU , Department of Radiation Oncology, Munich, Germany; 5 Università Cattolica del Sacro Cuore, Dipartimento di Diagnostica per Immagini, Radioterapia Oncologica ed Ematologia, Roma, Italy; 6 Ospedale San Pietro Fatebenefratelli di Roma, Radiation Oncology, Roma, Italy; 7 University Hospital LMU, Department of Radiation Oncology, Munich, Germany; 8 Heidelberg University Hospital, Heidelberg Ion-Beam Therapy Center (HIT), Department of Radiation Oncology, Heidelberg, Germany Purpose or Objective The optimal workflow for re-irradiation of Prostate Cancer (PC) local recurrences represents an emerging challenge in the era of advanced local re-treatment modalities. In this context, stereotactic body radiation therapy (SBRT) allows the delivery of curative doses, efficaciously sparing the surrounding OARs. Magnetic Resonance Guided Radiation Therapy (MRgRT) has shown promising results in terms of feasibility and efficacy of delivering SBRT thanks to the enhanced soft tissue contrast and the online adaptive workflow.