ESTRO 36 Abstract Book

S702 ESTRO 36 2017 _______________________________________________________________________________________________

regional relapse. Aim of the analysis is to evaluate the role of SRT +/- concomitant androgen deprivation therapy (ADT) in pts with clinical/radiological/metabolic loco-regional relapse. Material and Methods From 2007 to September 2015, fifty-five pts with locoregional macroscopic PCa relapse underwent radical SRT +/- concomitant/adjuvant ADT. Median age at time of SRT was 72 years. At time of diagnosis 32pts had pT2 PCa, 6 pT3a and 19 pT3b according to TNM AJCC Stratification. Only 4 pts had abdominal node involvement (pN+). Gleason Pattern Score was <7 in 8pts, 7 in 35 and >7 in 11 pts. At time of relapse all pts had an elevated PSA: 19 pts <1.0 ng/mL, 22 between 1.1-5 ng/ml and 15 pts >5 ng/mL. Before being submitted to SRT most pts (44/56) were staged with 18F-Choline CT-PET while 18 pts had also pelvic MRI to help with for a better RT planning. At the end of restaging 48/56 had just local relapse (prostatic bed), 3 nodal Involvement and 4 pts had both. Due to clinical stage and PSA value, 23 pts were previously submitted to first line ADT, while 6 pts received two or more ADT lines. Finally SRT was delivered in association to concomitant ADT in 25/56 pts in 13 of whom it was continued with an adjuvant approach Results At a median follow up of 36.2 months all pts but 3/56 (5%) were alive. All pts were treated with high dose RT (2.0- 2.5 Gy/day,28-37 total fractions) with or without concomitant ADT. Median RT dose was 70 Gy (range 62- 76Gy). Target volume encompassed prostatic bed and macroscopic lesion in 42 pts (75%), while in the other 14 pelvic abdominal RT was performed due to high risk of nodal involvement(in 10 pts with prophylactic intent, in 4 pts using a boost on 18F-Choline CT-PET positive nodes). Three- and 5-year actuarial OS were 97.6%(ES±2.4%) and 88.5%(ES±6.7%), respectively. Three- and 5-year actuarial Biochemical Free Survival were 71.4%(ES±6.9) and 56.7% (ES±9.4) respectively while Metastasis Free Survival 90.5% (ES±4.0%) and 81.2% (ES±6.5%). Nine pts (16%) experienced distant recurrences: bone lesions were found in 6 pts, while extra-pelvic nodes in 5 pts (2/9 pts had both). No grade 4 acute/late toxicities were found, only 1 pt had G3 late Gastrointestinal side effects Conclusion Our results of high dose SRT +/- ADT in pts with loco- regional macroscopic PCa relapse demonstrate an excellent profile in terms of oncological outcomes (OS, DFS, MFS) confirming again the important role of SRT even in this unfavourable subset of pts. EP-1322 Performance diagnosis of 11c-choline pet/ct in prostate cancer P.M. Samper Ots 1 , A. Luis Cardo 1 , M.A. Cabeza Rodriguez 2 , C. Vallejo Ocaña 3 , L.A. Glaria Enriquez 4 , M.L. Couselo Paniagua 5 , J. Olivera Vegas 6 1 Hospital Rey Juan Carlos, Servicio de Oncologia Radioterapica, Mostoles - Madrid, Spain 2 Hospital 12 de Octubre, Servicio de Oncologia Radioterapica, Madrid, Spain 3 Hospital Ramon y Cajal, Servicio de Oncologia Radioterapica, Madrid, Spain 4 Hospital La Paz, Servicio de Oncologia Radioterapica, Madrid, Spain 5 Hospital Gomez Ulla, Servicio de Oncología Radioterapica, Madrid, Spain 6 Fundación Jimenez Diaz, Servicio de Oncologia Radioterapica, Madrid, Spain Purpose or Objective To test the performance of 11C-choline PET/CT in staging and change the therapeutic decision in prostate cancer (PC). Correlation of prognostic factors with the detection of disseminated disease. Material and Methods macroscopic

Retrospective observational multicenter study in which 233 patients diagnosed with PC, median age was 68.21 years included. Inclusion criteria: 56 patients (24%) with high-risk localized PC, 102 patients (43.8%) with biochemical failure after surgery and 75 patients (32.2%) with biochemical failure after radiotherapy, all study negative extension (CT and bone scintigraphy). We collected the prognostic factors for PC diagnosis and surgical specimen: PSA, Gleason score, T stage, N stage, percentage of positive biopsies, perineural invasion and margins. And in patients with biochemical failure: the PSA, PSA doubling time (PSADT) and PSA velocity (PSAV) at the time of failure. The study was approved by the Ethics Committee for Clinical Research (CEIC) and meets the standards of data protection. For statistical analysis SPSS version 22.0 was used. Results The 11C-choline PETCT confirmed the diagnosis of the extension study only in 81 patients (34.7%), changed the therapeutic indication in 137 patients (58.8%) and confirmed metastatic disease in 127 patients (54.5%). Prognostic factors of diagnosis of metastasis in 11C- choline PETCT in the univariate analysis were: Primary Gleason ³ 4 (p = 0.002), secondary Gleason ³ 4 (p = 0.039), Gleason score ³ 8 (p = 0.001), perineural invasion in biopsy (p = 0.04), perineural invasion in the surgical specimen (p = 0.029), previous hormone therapy (p = 0.001), the PSA failure (p = 0.023), the PSADT (p = 0.023), and VPSA (p <0.001); in the multivariate analysis: primary Gleason diagnosis (p = 0.001, Gleason score at diagnosis (p = 0.002), PSA in failure (p = 0.005), PSA DT (p = 0.010) and VPSA (p = 0.000). Conclusion 11C-choline PET-CT has proven to be cost-effective for the detection of metastatic disease in high risk patients with primary Gleason ≥ 4 and Gleason score ≥ 8 diagnostic, and in patients with biochemical failure and kinetics elevated PSA, which involve a change in the therapeutic indication. EP-1323 Role of 68Ga-PSMA PET/CT in radiotherapy for prostate cancer: A single centre experience N.S. Hegemann 1 , W.P. Fendler 2 , A. Buchner 3 , C. Stief 3 , M. Niyazi 1 , P. Bartenstein 2 , C. Belka 1 , U. Ganswindt 1 1 Klinik und poliklinik für Strahlentherapie und Radioonkologie, Radiation Oncology Ludwig-Maximilians- University, München, Germany 2 Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany 3 Urology, Ludwig-Maximilians-University, Munich, Germany Purpose or Objective The aim of this study was to determine the potential role of 68 Ga-PSMA PET/CT in radiotherapy (RT) for prostate cancer. Material and Methods A retrospective analysis of 129 patients (pts) with available 68 Ga-PSMA PET/CT (Feb. 2014 - Aug. 2016) was performed. Potentially influencing factors (androgen deprivation therapy at time of PET/CT, injected amount of 68 Ga-PSMA-HBED-CC, PSA doubling time ≤/> 10 months, PSA before PET/CT, T-/N-category and Gleason score) were evaluated by uni- and multivariate binary logistic regression analysis. The detection rate of 68 Ga-PSMA PET/CT compared to contrast enhanced CT and its impact on RT management was analysed. Results 129 pts (20 at initial diagnosis, 49 with PSA relapse and 60 with PSA persistence after radical prostatectomy) received 68 Ga-PSMA PET/CT prior to RT. The majority of pts (71.3%) had 68 Ga-PSMA PET/CT positive findings (55.1% of pts with PSA recurrence, 75% of pts with PSA persistence and 100% of newly diagnosed pts). The uni- and multivariate analysis found no significant association between PET-positive results and above mentioned factors