Abstract Book

S837

ESTRO 37

Purpose or Objective Bone is the most common site of metastatic disease in advanced prostate cancer. Radium-223 ( 223 Ra) is a calcium mimetic alpha particle emitter, which has been shown to have good activity in prostate cancer with symptomatic bone metastasis. Data on the use of less than 6 cycles of 223 Ra in prostate cancer are limited. Although there have been studies in assessing the clinical outcomes in patients who received 6 cycles of Ra 223 , there is very little information about the experience in patients receiving less than 6 courses of this radionuclide therapy. Material and Methods Mount Vernon Cancer Centre (MVCC) is one of the largest provider of 223 Rain the UK and patients with hormone refractory metastatic prostate cancer who were treated at this centre from May 2014 to August 2016 were included in our retrospective study. We identified 113 patients with a median age of 76 (52-92), who received 223 Ra at our centre. The median number of cycles administered was 5 (1-6) with 54 (48%) completing 6 cycles of the treatment. 85 patients (75%) received 223 Ra prior to docetaxel and 28 (25%) received it post docetaxel. Results 11 patients developed grade 2 or 3 thrombocytopenia with none of these patients completing any further 223 Ra. Only 25% of patients who had a haemoglobin of 10g/dl and below at the start of the treatment were able to complete 6 courses of 223 Ra. Of the patients who completed less than 6 cycles of 223 Ra (1-5 cycles), the survival was 121 days, as compared to 385 days in men who received 6 cycles of 223 Ra (odds ratio: 4.767, 95% CI 1.07-21.25; p=0.0005) Conclusion To our knowledge, no prior studies have evaluated outcomes in patients, based on number of treatment cycles of 223 Ra administered in prostate cancer. Careful selection of patients is essential to get good clinical outcomes and avoid use of treatment in whom there is less chance of completing 6 cycles of therapy. We propose reviewing Hb at the start of treatment, and monitoring platelet count closely during cycles, to act as a surrogate marker to predict whether patients are thus likely to complete 6 cycles of 223 Ra. EP-1553 Prognostic Role of NLR after radical surgery and postoperative radiotherapy for prostate cancer A. Hervas Moron 1 , D. Candini 1 , M. Martin 1 , J. Dominguez 1 , F. Lopez 1 , E. Carrasco 1 , M. Vallejo 1 , S. Sancho 1 1 Hospital Ramon y Cajal, Radiation Oncology, Madrid, Spain Purpose or Objective The prognosis role of neutrophil-to-lymphocyte ratio (NLR) in patients with prostate cancer remains inconsistent. Therefore, we conducted this study to analize the results of adjuvant and salvage radiotherapy after radical prostatectomy and to determine prognostic significance of early postoperative NLR in postoperative We retrospectively reviewed clinical data from 302 patients with localized prostate cancer who underwent radical prostatectomy at our institution over a 12-year period and received postoperative radiotherapy (adjuvant or salvage). Overall survival and biochemical-relapse free survival were calculated using Kaplan-Meier and prostate cancer setting. Material and Methods

EP-1551 Outcome after PSMA PET based RT in patients with biochemical recurrence or persistence after surgery N.S. Schmidt-Hegemann 1 , W. Fendler 2 , C. Stief 3 , P. Bartenstein 2 , U. Ganswindt 4 , C. Belka 1 1 University Hospital Munich, Radiation Oncology, München, Germany 2 University Hospital Munich, Nuclear medicine, Munich, Germany 3 University Hospital Munich, Urology, Munich, Germany 4 Medizinische Universität Innsbruck, Radiation Oncology, Innsbruck, Austria Purpose or Objective PSMA PET/CT visualizes prostate cancer recurrences or residua at much lower PSA levels and results in a remarkable high number of patients in a change of treatment. Dose escalation of the former prostate bed has been associated with improved biochemical recurrence free survival. Thus, it can be hypothesized that PSMA PET/CT based radiotherapy might even lead to 129 patients underwent PSMA PET/CT due to biochemical recurrence (48%) or persistence (52%) after radical prostatectomy without evidence of distant metastases (February 2014 - May 2017) and received PSMA PET/CT based radiotherapy. Results Patients with biochemical persistence were significantly more often high-risk patients with significantly shorter time until PSMA PET/CT than patients with biochemical recurrence. PSMA PET/CT resulted in patients with biochemical recurrence significantly more often in no evidence of disease or local recurrence only whereas patients with biochemical persistence had significantly more lymph node metastases. With evidence of macroscopic disease antiandrogen therapy was started in 73 patients. Overall doses ranged from 70 Gy to local macroscopic tumor, 66 Gy to the prostate fossa, 61.6 Gy to PET-positive lymph nodes to 50.4 Gy to lymphatic pathways. Median PSA after radiotherapy was 0.07 ng/ml with 74% of patients with a PSA ≤0.1 ng/ml. After a median follow-up of 20 months, median PSA of all patients was 0.07 ng/ml with 30 patients with ongoing antiandrogen therapy. PET-positive patients with no antiandrogen therapy at last follow-up (45 patients) had a median PSA of 0.05 ng/ml with 78% of all patients, 93% of patients with biochemical recurrence and 56% of patients with biochemical persistence having a PSA ≤ 0.2 ng/ml. Achieving a PSA ≤ 0.1 ng/ml post- radiotherapy and belonging to the group of patients with biochemical recurrence was significantly associated with a PSA ≤ 0.2 ng/ml at last follow-up. Conclusion PSMA PET/CT based radiotherapy is an effective local salvage treatment with significant treatment response in term of PSA in patients with locoregional recurrence or persistence after prostatectomy. It can delay the necessity of long-term ADT or systemic therapy. EP-1552 single centre experience of the use of Radium-223 with clinical outcomes based on number of cycles S. Dadhania 1 , R. Alonzi 1 , S. Douglas 1 , A. Gogbashian 1 , R. Hughes 1 , Z. Danube 1 , N. Vasdev 1 , C. Westbury 1 , N. Anyamene 1 , P. Ostler 1 , P. Hoskin 1 , A. Sharma 1 1 Mount Vernon Cancer Centre, Department of Oncology, Northwood, United Kingdom a further improvement. Material and Methods