ESTRO 38 Abstract book

S820 ESTRO 38

Purpose or Objective Radical prostatectomy (RP) is an effective and widely used curative treatment for localized prostate cancer while salvage radiotherapy (SRT) is recommended for biochemical relapse (BR) after prostatectomy (RP). Even if several studies showed that biochemical control can be achieved by SRT if it starts as sooner as possible several patients (pts) are still referred to Radiation Oncologists when macroscopical recurrence has occured. This is a final update analysis of a multicenter retrospective study to evaluate SRT efficacy and tolerability in pts with biopsy/imaging proven relapse. Material and Methods We retrospectively analyzed 105 pts with macroscopic relapse after RP who underwent SRT between 2001 and 2016. We identify subgroups by means of nodal involvement (N0 vs N1) at diagnosis, Gleason Score (≤7 Vs >8-10), PSA value at relapse (≤2.0 ng/mL Vs >2.0 ng/mL), restaging (biopsy Vs TC scan/MRI Vs Choline CT-PET) and concomitant hormone therapy (Yes/No). Survival curves were generated using Kaplan-Meier method and relationship with outcome were analyzed using univariate followed by Cox regression analysis. Results After a median follow up of 52 months, 89 pts were still alive. Total RT dose to macroscopic lesion was >70 Gy in 58 pts, ≤70 Gy in 43 pts. Exclusive SRT was used in 42 pts, while 63 received also concomitant ADT. Five and ten-year overall survival was 85,5% and 76,1% while distant metastasis free survival was 86,1% and 73,3% respectively. In 30 pts prophylactic RT was delivered to pelvic nodal stations. Five and 10-year-OS was 85,5%±4,4 Standard Error (SE) and 76,1%±5,9SE while MFS was 86,1±3,6SE and 73,3±5,9SE respectively. Five and 10-year-bPFS was 69.7±5.2SE and 57.7±6.6SE, respectively. Extrapelvic nodal relapse was found in 5 pts, bone metastasis in 12, both in 2. No grade 4/5 toxicities were found. Conclusion SRT even in pts with loco-regional macroscopic PCa relapse results in an excellent profile in terms of oncological outcome (OS, BFS , MFS) confirming the role of SRT even in this unfavorable subset of pts. In comparison with available series treated with ADT only, our data suggest that SRT may either postpone ADT or improve results over ADT alone in appropriately selected pts. EP-1517 The long-term result of stereotactic body radiotherapy for localized prostate cancer Y. Lin 1 , S. Wang 1 1 Chi Mei Medical Center, Department of Radiation Oncology, Tainan, Taiwan Purpose or Objective The understanding of radiobiology for prostate cancer suggested hypofractionation might achieve a higher therapeutic benefit. Stereotactic body radiation therapy (SBRT) is able to deliver a high dose per fraction precisely. SBRT for prostate cancer could escalate biological effective doses while without increasing toxicity. Here, we reported our long-term results of SBRT for localized prostate cancer. Material and Methods Between November 2008 and May 2018, a total of 232 patients with clinically localized prostate were enrolled for analysis. Patients were low-risk (11%), intermediate- risk (37%), and high-risk (52%). Low- and intermediate-risk patients were treated with SBRT to prostate and half of seminal vesicles (37.5Gy in 5 fractions). High-risk patients were treated with whole pelvic irradiation (45Gy in 25 fractions) and SBRT boost (21Gy in 3 fractions). The intermediate- and high-risk patients received hormone therapy with different duration. The toxicities of gastrointestinal (GI) and genitourinary (GU) tracts were scored by Common Toxicity Criteria Adverse Effect (CTCAE

EP-1515 Substantial impact of 68Ga-PSMA-PET/CT on the radiotherapeutic approach for prostate cancer N. Schmidt-Hegemann 1 , C. Eze 1 , M. Li 1 , P. Rogowski 1 , C. Schaefer 1 , C. Stief 2 , U. Ganswindt 3 , P. Bartenstein 4 , C. Belka 1 , H. Ilhan 4 1 Department of Radiation Oncology- University Hospital- LMU Munich, Department of Radiation Oncology- University Hospital- LMU Munich, München, Germany ; 2 Klinik und poliklinik für Urologie, Department of Urology - University hospital Munich, München, Germany ; 3 Department of Therapeutic Radiology and Oncology - Medical University Innsbruck, Department of Therapeutic Radiology and Oncology - Medical University Innsbruck, Innsbruck, Austria ; 4 Department of Nuclear Medicine- University Hospital- LMU Munich, Department of Nuclear Medicine- University Hospital- LMU Munich, München, Germany Purpose or Objective Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) offers unprecedented accuracy for staging of primary, persistent or recurrent prostate cancer. Thus, we hypothesized that PSMA PET/CT prior to radiotherapy significantly impacts the radiotherapeutic approach. Material and Methods Between February 2014 and December 2017, a total of 172 patients received PSMA PET/CT and were included in this retrospective analysis. Twenty-two (13%) patients were referred for primary definitive radiotherapy, 51% (88/172) for PSA persistence and 36% (62/172) for PSA recurrence after radical prostatectomy. The potential increase in diagnostic accuracy, and the subsequent change of radiotherapeutic approach was documented separately for PET/CT versus CT. Results Overall detection rate was 70% (120/172) in 68Ga-PSMA PET/CT. Patients with pre-PSMA PET/CT PSA-level >0.5 ng/ml (98/111; 88%) had significantly more often PET- positive results. Overall, PSMA PET/CT revealed a total of 171 lesions, PET alone 156 and CT alone 85. For all patients a continuous diagnostic increase in positive findings was observed for primary tumor/local recurrence (CT: 18% vs. PET/CT: 37%), pelvic lymph node (CT: 21% vs. PET/CT: 44%) and distant metastases (CT: 7% vs. PET/CT: 19%) when comparing CT vs. PET/CT. Compared to CT, the combination of PET/CT information resulted in a change of treatment in 107/172 (62%) patients, i.e. 8/22 (36%) patients prior to any treatment, 31/62 (50%) with PSA recurrence and 68/88 (77%) with PSA persistence. Comparing the different radiotherapy indications with each other, there was a higher change of management in postoperative patients vs. patients prior to any treatment. Conclusion Compared to conventional CT, PSMA PET/CT had a remarkable impact on radiotherapeutic approach especially in postoperative patients. Postoperative patients might benefit in particular from an improved staging method, as for patients with persistent or recurrent prostate cancer there are no nomogram-based radiotherapy treatment volumes. EP-1516 Macroscopic local relapse from prostate cancer: which role for salvage RT? An update analysis A. Bruni 1 , G. Ingrosso 2 , F. Trippa 3 , M. Di Staso 4 , L. Rubino 1 , G. Aluisio 1 , S. Parente 4 , L. Frassinelli 1 , E. Maranzano 3 , R. Santoni 2 , E. Mazzeo 1 , F. Lohr 1 1 Az. Ospedaliero-Universitaria di Modena - Policlinico, Radiation Oncology Department, Modena, Italy ; 2 “Tor Vergata” University General Hospital, Radiotherapy Unit-, Rome, Italy ; 3 "Santa Maria" University Hospital, Radiotherapy Unit, Terni, Italy ; 4 “Nuovo San Salvatore” Hospital, Radiotherapy Unit, L’Aquila, Italy