ESTRO 2020 Abstract book

S662 ESTRO 2020

From 2002 to 2016, we retrospectively evaluate 448 patients with histologically confirmed high-risk prostate cancer defined by National Comprehensive Cancer Network (NCCN) risk group were included. All patients received RT and ADT. Biochemical relapse was established by Phoenix criteria (PSA concentration superior than nadir plus 2 ng/ml) and the presence of metastasis was radiographically confirmed. We analyze survival using Kaplan-Meier method. Results Demographic characteristics of patients are showed in Table 1. Median follow-up was 88 months. At 5 and 10 years DSS was 98.7% and 96.9%, BFFS was 86.7% and 75%, DFFS was 93% and 84.8% while RFFS was 91.5% and 87.9, respectively. Pelvic node radiation provides a significant improvement in RFFS at 88 months versus no pelvis radiation (97% versus 85%; p= 0.00) but not a better OS (84.2% versus 81%; p=0.2). Acute genital-urinary and gastro-intestinal toxicity was acceptable (only 1.3% and 1.8% ≥ grade 3, respectively) and also chronic toxicity was limited (5,6% and 1.6% ≥ grade 3, respectively). Conclusion Overall, in our experience combination of WPRT with ADT provides an excellent local control with high DSS rate and tolerable toxicity. Finally, patients treated with nodal pelvis radiation showed best outcomes. PO-1169 Influence of localisation of PSMA-positive oligo-metastases on efficacy of metastasis-directed EBRT N. Schmidt-Hegemann 1 , S. Kroeze 2 , C. Henkenberens 3 , M. Vogel 4 , S. Kirste 5 , J. Becker 6 , I. Burger 7 , T. Derlin 8 , P. Bartenstein 9 , M. Eiber 10 , M. Mix 11 , C. Lafougere 12 , A. Müller 6 , A. Grosu 5 , S. Combs 4 , H. Christiansen 3 , M. Guckenberger 2 , C. Belka 1 1 Department of Radiation Oncology, University Hospital LMU Munich, München, Germany ; 2 Department of Radiation Oncology, University Hospital Zürich, Zürich, Switzerland ; 3 Department of Radiotherapy and Special Oncology, Medical School Hannover, Hannover, Germany ; 4 Department of Radiation Oncology, Technical University of Munich, Munich, Germany ; 5 Department of Radiation Oncology, University of Freiburg, Freiburg, Germany ; 6 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany ; 7 Department of Nuclear Medicine, University Hospital Zürich, Zürich, Switzerland ; 8 Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany ; 9 Department of Nuclear Medicine, University Hospital LMU Munich, Munich, Germany ; 10 Department of Nuclear Medicine, Technical University Munich, Munich, Germany ; 11 Department of Nuclear Medicine, University of Freiburg, Freiburg, Germany ; 12 Department of Nuclear Medicine, University Hospital Tübingen, Tübingen, Germany Purpose or Objective Approximately 40-70% of biochemically persistent or recurrent prostate cancer (PCa) patients after radical prostatectomy (RPE) are oligo-metastatic in 68 Gallium- prostate-specific membrane antigen positron emission tomography ( 68 Ga-PSMA PET). Those lesions are frequently not cured by the current standards of care like external- beam radiotherapy (EBRT) of the prostatic fossa. This retrospective study analyses the influence of oligo- metastases’ site on outcome after metastasis-directed radiotherapy (MDR). Material and Methods Retrospectively, 359 patients with PSMA PET-positive PCa recurrences after RPE all treated with MDR were analyzed. Patients with prior salvage treatments were excluded. Biochemical recurrence-free survival (BRFS) (PSA < post- radiotherapy nadir + 0.2ng/mL) was assessed using Kaplan-

PO-1167 Salvage therapies for PSMA PET-positive nodal recurrent prostate cancer N. Schmidt-Hegemann 1 , C. Eze 1 , P. Rogowski 1 , C. Schaefer 1 , M. Li 1 , A. Buchner 2 , W.P. Fendler 3 , P. Bartenstein 4 , U. Ganswindt 5 , C. Stief 2 , C. Belka 1 , A. Kretschmer 2 1 Department of Radiation Oncology, University Hospital- LMU Munich, München, Germany ; 2 Department of Urology, University Hospital- LMU Munich, München, Germany ; 3 Department of Nuclear Medicine, University Hospital Essen, Essen, Germany ; 4 Department of Nuclear Medicine, University Hospital- LMU Munich, München, Germany ; 5 Department of Therapeutic Radiology and Oncology, Innsbruck Medical University, Innsbruck, Austria Purpose or Objective This analysis compares salvage lymph node dissection (SLND) to salvage lymph node radiotherapy (SLNRT) of 68 Ga-PSMA PET-positive nodal recurrences after radical 67 SLNRT and 33 SLND patients with pelvic and/or paraaortic nodal recurrences after RPE were retrospectively analyzed. Biochemical recurrence-free survival (BRFS) (PSA < 0.2 ng/mL) was assessed using Kaplan-Meier survival curves and log rank. For multivariable analysis, binary logistic regression analysis was performed (p<0.05). Results Median follow-up was 17 months (6 - 53) in SLND patients and 31 (3 - 56) in SLNRT patients (p= 0.027). SLNRT patients had significantly more T3/4 stages (82% vs. 67%; p= 0.006), pathologic lymph nodes (45% vs. 27%; p= 0.001) and positive surgical margins (54% vs. 12%; p= 0.001) at time of RPE than SLND patients. PSA persistence after RPE was significantly more frequently observed in the SLNRT cohort (73% vs. 27%; p= 0.001). There was no significant difference in the distribution of PET-positive lymph nodes. Median PSA before SLND was higher than before SLNRT (3.07 ng/ml vs. 1.3 ng/ml; p= 0.393). Overall, BRFS was significantly longer in the SLNRT vs. the SLND cohort (92% vs. 30%; p= 0.001) with lower rates of distant metastases (21% vs. 52%; p= 0.002) and secondary treatments (5% vs. 39%; p= 0.011) irrespective of ongoing androgen deprivation therapy at last contact. In multivariable analysis, SLNRT was significantly associated with prolonged BRFS (regression coefficient 1.436, hazard ratio 4.204, 95% CI 1.789 - 9.878; p=0.001). Conclusion This retrospective study indicates longer BRFS in patients undergoing PSMA PET-informed SLNRT as compared to SLND for recurrent prostate cancer. PO-1168 Radiotherapy in high risk prostate cancer: Whole pelvic radiotherapy vs prostate only radiotherapy A. Hernández 1 , L. Pelari 1 , G. Caddedu 1 , I. Císcar 1 , K. Ytuza 1 , S. Sastre 1 , E. Carrasco 1 , F. López 1 , C. Vallejo 1 , S. Sancho 1 , A. Hervás 1 1 Ramón y Cajal University Hospital, Radiation Oncology, Madrid, Spain Purpose or Objective We present the experience of our Radiation Oncology Department with high-risk prostate cancer patients, seen over a period of 14 years. We analyzed preliminary clinical results of a retrospective cohort of high-risk prostate cancer patients treated with External Beam Radiation Therapy (EBRT) to determine whether WPRT or prostate- only radiotherapy (PORT) yields improved Disease- Specific-Survival (DSS), Biochemical-Failure-Free-Survival (BFFS), Distant-Failure-Free-Survival (DFFS) and Regiona- Failure-Free-Survival (RFFS). Material and Methods prostatectomy (RPE). Material and Methods