ESTRO 2023 - Abstract Book

S1205

Digital Posters

ESTRO 2023

therapeutic solution. The aim of the study is to evaluate safety and efficacy of Linac-based SBRT in patients affected by PC Materials and Methods Men affected by localized PC were enrolled and analyzed. The SBRT schedule consisted of the administration of 35 Gy in 5 fractions using Volumetric Modulated Arc Therapy (VMAT) in 1 or 2 weeks depending on total target volume and baseline urinary symptom. An androgen deprivation therapy (ADT) was prescribed in some cases on the basis of risk class classification. Treatment related toxicity was evaluated at the end of treatment, 2 weeks after SBRT and during follow-up (FU) and described according the Common Terminology Criteria for Adverse Events. (CTCAE). PSA values were measured and recorded before treatment, two weeks after the end of therapy and during FU as biochemical response criteria. Results Between July 2019 and September 2021, 156 patients were treated. Median age was 75 years (range 50-86); 42% were in the low-risk group, 42% in the favorable/unfavorable intermediate-risk group and 16% in the high-risk group. Median pre treatment PSA was 6,36 ng/ml (range 0,2-49,5 ng/ml). ADT was administrated in 65 patients (42%). Median PTV was 101.7 cc (range 51-192,2). Median baseline IPSS was 6 (range 0-19). At the end of treatment, no >G1 acute toxicity was observed. Two-three weeks after the end of the treatment, 7 patients (4,5 %) reported G2 acute genitourinary toxicity (urinary frequency, urinary tract pain and urinary retention), while 21 patients (13,5 %) reported rectal tenesmus. During the last FU, no late toxicity and no relevant deteriorations of QoL were described. At a median FU of 23 months (range 8-35), an excellent biochemical disease control was achieved in all cases with a median PSA of 0,5 ng/ml (range 0-7,21). Conclusion Ultra-hypofractionated Linac-based SBRT in patients affected by localized PC is feasible and well tolerated and leads to an excellent biochemical disease control. Purpose or Objective The aim of this mono-institutional retrospective study was to evaluate the outcomes and toxicities of local re-irradiation with stereotactic body radiation therapy (SBRT) in patients with local recurrence of prostate cancer after curative radiotherapy. Materials and Methods Thirty patients were enrolled in this study. All patients presented clinical and radiological local relapse in the prostate and no distant metastasis diagnosed with multi-parametric magnetic resonance and Choline PET-TC. All of them were treated with SBRT between December 2010 and May 2022. Twenty four patients (80%) received 30 Gy in 5 fractions/3w, 3 (10%) received 25 Gy in 5 fractions/3w, 2 (7%) received 23 Gy in single fraction and 1 (3%) received 27.5 Gy in five fractions/3w. All patients underwent image-guided radiotherapy (IGRT) using cone-beam computed tomography (CBCT) system as daily pre-treatment imaging. Twelve out of 30 patients (40%) received also hormonal deprivation therapy. Toxicity was evaluated using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer Criteria. Biochemical control was assessed according to the Phoenix definition (NADIR + 2 ng ml (-1)). Results Median actuarial follow-up was 36.7 months (95% CI 21.07-52.32, range 1.6 – 85.3). Median age was 78 years (range 66-89 years), median pre-SBRT prostate specific antigen (PSA) was 3.79 ng ml (range 0.05-20 ng/ml). The median planning target volume (PTV) was 63 cm3 (range 9-149 cm3). Five and 10-year overall survival (OS) from primary diagnosis were 96.7% and 83.2%, respectively. Median, 1 and 3-year OS from re-irradiation were 63.7 months (95% IC 54.27-73.12), 96.7% and 80.7%, respectively. One and 3-year biochemical free survival (BFS) were 82.1% and 43.7%, respectively. One and 3-year local control (LC) were 92.3% and 58.1%, respectively. One and 3-year disease free survival (DFS) were 85.7% and 44.9%, respectively. One and 3-year metastasis free survival (MFS) were 96.2% and 73.6%, respectively. Median LC and MFS were not reached. Eight patients (27%) experienced grade 1-2 acute urinary toxicities . Grade 1-2 late urinary toxicities were reported in 10 patients (33%). Three patients (10%) experienced grade 1-2 acute gastrointestinal toxicities . Three patients (10%) experienced grade 1-2 late gastrointestinal toxicities. Conclusion SBRT re-irradiation for local recurrent prostate cancer offers a satisfactory tumor control and shows a low toxicity profile. PO-1488 Local recurrence of prostate cancer after curative RT: the role of salvage SBRT re-irradiation R.C. Sigillo 1 , G. Facondo 1 , A. Bertozzi 1 , G. Vullo 1 , M.F. Osti 1 , M. Valeriani 1 1 Sapienza Università di Roma, AOU Sant'Andrea Roma, UO Radioterapia Oncologica, Rome, Italy

PO-1489 MRI sensitivity in detecting macroscopic local recurrences in prostate cancer:an observational study

L. Cavallini 1 , C. Gaudiano 2 , A. Arcelli 3 , E. Galietta 1 , F. Mammini 1 , D. Vallerossa 1 , V. Laghi 1 , S. Paolinelli 1 , E. Natoli 1 , G. Tolento 3 , S. Cammelli 1 , A.G. Morganti 1 , M. Ntreta 3 1 Radiation Oncology, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Alma Mater Studiorum University of Bologna, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 2 Department of Radiology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 3 Radiation Oncology, IRCCS Azienda Ospedaliero Universitaria di Bologna, Bologna, Italy