Abstract Book

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ESTRO 37

Results A total of 15 patients were accrued to each protocol arm. Within a median follow-up of 16 months (range, 11-24), no grade ≥2 acute GI or GU toxicities were observed in either group. Grade 1 GU and GI toxicities were 18% and 0% in the hypo arm respectively, and 41% and 8% in the SDRT arm respectively. There were no significant differences in mean EPIC scores in all domains. An initial 6% and 8% drop in the EPIC urinary domain score occurred in the hypo and SDRT arm respectively, returning to baselines by 3 months. Similarly, at one month median IPSS values increased from 7 to 11 and from 7 to 10, in the hypo and SDRT arms respectively, returning to baseline by 3-months. PSA reduction kinetics were also similar between the two regimens, reaching ≤1 ng/mL by 18 months. Of note, all cases, regardless of treatment regimen, converted to non-detectable disease on mutiparametric MRI. Patients in this trial will receive a planned 24 months post-treatment biopsy to validate treatment outcome. Conclusion These early trial outcomes indicate that 24Gy SDRT can be consistently and safely delivered, yielding the same low acute toxicity as demonstrated with the hypo 5x9Gy schedule , and is associated with excellent QoL measures. Further planned endpoints (i.e. late toxicity, long-term biochemical outcomes, and 24 months post-treatment biopsy) are pending. PV-0622 Impact and efficacy of 68GA-PSMA PET/CT in recurrent prostate cancer patients with PSA <0.5 ng/ml G. Siepe 1 , M. Buwenge 1 , I. Capocaccia 1 , A. Farolfi 2 , T. Graziani 2 , P. Castellucci 2 , M. Ntreta 1 , G. Macchia 3 , F. Deodato 3 , S. Cilla 4 , S. Cammelli 1 , G.P. Frezza 5 , S. Fanti 2 , A.G. Morganti 1 1 Radiation Oncology Center- Dept. of Experimental- Diagnostic and Specialty Medicine – DIMES, University of Bologna- S.Orsola-Malpighi Hospital, Bologna, Italy 2 Service of Nuclear Medicine, S.Orsola-Malpighi Hospital- University of Bologna, Bologna, Italy 3 Radiotherapy Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 4 Medical Physics Unit, Fondazione di Ricerca e Cura “Giovanni Paolo II”, Campobasso, Italy 5 Radiation Oncology Unit, Bellaria Hospital, Bologna, Italy Purpose or Objective Primary goal of this retrospective analysis was to assess the performance of 68Ga-PSMA-PET/CT in biochemical recurrence (BCR) after radical prostatectomy (RP)prostate cancer (PCa) patients with serum PSA level (PSA) lower than 0.5 ng/mL. The secondary aim was to evaluate the potential impact of 68Ga-PSMA PET/CT on radiotherapy treatment planning process. Material and Methods 68Ga-PSMA-PET/CT is performed in our institution in an investigational new drug (IND) trial in PCa patients with BCR. We retrospectively analyzed record of all patients enrolled between March 2016 and July 2017. We selected patients matching all the following criteria: BCR with PSA values between 0.2 - 0.5 ng/mL and RP as primary therapy. The performance of 68Ga-PSMA-PET/CT was evaluated as detection rate on a per-patient and a per- region basis (local vs. distant lesions). We also performed an intention-to-treat (ITT) analysis dividing our cohort of patients, in a blinded setting about PSMA results, into 5 sub-groups: a) active surveillance (AS), b) salvage radiotherapy (S-RT) candidates (± systemic treatment), c) stereotactic body RT (SBRT) candidates (± systemic treatment), d) pelvic lymph node dissection (PLND) and e) androgen-deprivation therapy (ADT) alone, according to NCCN Guidelines. A regression analysis was performed to investigate, among the available clinical parameters, which one best correlated overall PET/CT detection rate

Poster Viewing : Poster viewing 12: Prostate

PV-0621 Single-Dose SBRT for Intermediate-risk prostate cancer: Early results from a randomized trial. C. Greco 1 , N. Pimentel 1 , O. Pares 1 , M. Possanzini 1 , V. Louro 1 , X. Morales 1 , S. Viera 1 , J. Stroom 1 , D. Mateus 1 , B. Nunes 1 , Z. Fuks 1 1 Fundação Champalimaud, Radiation Oncology, Lisboa, Portugal Purpose or Objective To report initial response, acute treatment-related toxicity and patient-reported quality of life (QoL) after Single-Dose SBRT (SDRT) at a prescription dose of 24Gy from a randomized Phase II study of patients with histologically proven intermediate-risk adenocarcinoma of the prostate (NCCN definition). Material and Methods Between November 2015 and December 20 16, 30 hormone-naïve patients were enrolled in an IRB-approved prospectively randomized phase II study to receive either 45Gy in 5 consecutive daily fractions (Hypo-SBRT) or 24Gy SDRT. This protocol was based on a previous phase I/II single arm hypofractionated study of intermediate-risk prostate cancer (5x9Gy daily, in 200 patients accrued between 05/2013 and 09/2016) and a phase I pilot study of 24Gy SDRT of stage IV prostate cancer with radiation- and surgery-naïve prostates failing androgen ablation using the same technique as implemented in the presently reported randomized trial. Treatment in both arms was based on VMAT-IGRT with urethral sparing via a dose-painting technique and real- time motion management with beacon transponders. The PTV included the prostate gland and seminal vesicles, and a 2 mm margin beyond the CTV. Precise PTV targeting and anatomical reproducibility was achieved via placement of an endorectal air-filled balloon (150 cc) and a Foley catheter. This setup also conferred organ motion mitigation, and online tracking ensured treatment delivery within the 2 mm PTV margin. Genito-urinary (GU) and gastro-intestinal (GI) toxicity were graded according to the NCI CTCAE v.4, and QoL was assessed by EPIC and IPSS questionnaires. Tumor response was assessed biochemically (PSA) and by follow-up MRI at 3 months after treatment and at 6 months intervals thereafter.