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Figure 2: Pairwise DSC analysis between observers across all patients. Conclusion Significant variation in observer contouring for MR pelvic structures was observed. Studies incorporating these structures should assess the accuracy and reproducibility of observer contours before proceeding with investigations.

treated with primary radiochemotherapy in our medical center. Material and Methods Retrospective analysis of bladder cancer patients receiving radiation therapy in our hospital between the years 2005-2015 Data collection included demographic information, tumor grade and stage at diagnosis, radiation therapy protocol, chemotherapy and survival. Results 155 patients with a diagnosis of bladder cancer were treated in our radiation therapy institute during the years 2005-2015. 94 patients completed a definitive radiation therapy (≥55Gy) for invasive bladder cancer. 43 patients received either cisplatin (20) or carboplatin (23) during the radiation period. Median age of the patients was 74.9 years (range 40.4 – 91.7 years), 83 males and 11 females. Mean follow up was 39.4 months. Overall survival for the entire cohort of patients was 39% in 5 years (median – 31.8 months). For those who were younger than 70y (no -28) the median overall survival was 63.6 months (52% the rate of 5-year survival, p=0.019). The median OS in the group of patients (no – 43) that received concomitant chemoradiation was 50.8 months vs 22.7 months in the group of radiotherapy (p=0.034).We studied influence of radiotherapy treatment parameters such as day dose (2Gy vs 1.8Gy)/total dose (60 Gy vs more than 60 Gy)/boost dose (≥ 16 Gy or less) on OS, but did not find statistical significance. Conclusion Radiation therapy for locally advanced bladder cancer in our series is effective as is in larger series reported in the literature although our patients were older and partially treated with concurrent chemotherapy. Radiochemotherapy should be indicated for those patients who cannot undergo radical cystectomy and might be offered as an alternative approach to surgery for appropriate patients. EP-1617 Development and evaluation of a MRI based delineation guideline for renal cell carcinoma F.M. Prins 1 , L.G.W. Kerkmeijer 1 , J.R.N. Voort van Zyp 1 , W.S.C. Eppinga 1 , H.D. Heerkens 1 , J.J.W. Lagendijk 1 , R.H.N. Tijssen 1 , E.P.A. Vonken 2 , A.N.T.J. Kotte 1 , M.M. Barendrecht 3 , W. Chu 4 , M.P.W. Intven 1 1 UMC Utrecht, Radiation Oncology, Utrecht, The Netherlands 2 UMC Utrecht, Radiology, Utrecht, The Netherlands 3 TerGooi Hospital, Urology, Hilversum, The Netherlands 4 Odette Cancer Centre- Sunnybrook Health Sciences Centre- University of Toronto- ON, Radiation Oncology, Toronto, Canada Purpose or Objective For renal cell carcinoma (RCC), surgery is standard of care. However, there is a need for non-invasive treatment alternatives like stereotactic body radiotherapy (SBRT). Nowadays, SBRT for RCC is mainly CT based with tumor delineation using CT and Cone-Beam CT (CBCT) guided dose delivery. SBRT for RCC could be optimized with the introduction of MR guided radiotherapy systems, like the MRI-Linac (MRL), in which real time MR imaging during dose delivery is possible. As a consequence of the introduction of MRI in the radiotherapy treatment of RCC, there is a need for guidelines on the delineation of RCC on MRI. In this study an RCC delineation guideline using MRI was developed and evaluated.

Electronic Poster: Clinical track: Urology-non-prostate

EP-1615 Tri-modalities for bladder cancer in elderly: TUR, hypofractionated radiotherapy and gemcitabine H. Hamza Abbas 1 , M. Salem 2 , A. Gbre 3 , M. Engaar 4 1 South Egypt Cancer Institute - Assiut Unversity, RADIATION ONCOLOGY, Assiut, Egypt 2 South Egypt Cancer institute assiut unvesity, Surgical Oncology, Assiut, Egypt 3 South Egypt Cancer institute, medical oncology, Assiut, Egypt 4 faculty of medicine assiut unversity, clinical oncology, Assiut, Egypt Purpose or Objective A prospective phase II study carried to evaluate hypofractionated radiotherapy with concurrent gemcitabine for bladder preservation in elderly. Material and Methods Patients and methods: Thirty-one patients enrolled, their age ≥ 65 years, diagnosed transitional cell carcinoma (TCC) of the urinary bladder with clinical stage T2 or T3, N0, M0, after maximum safe transurethral resection of the bladder tumour. They received 52.5 Gy in 20 fractions using 3DCRT with concurrent gemcitabine 100 mg/m2 weekly as a radio-sensitizer Results All patient completed their radiation therapy course, while seven patients received their chemotherapy irregularly due to G 3 toxicities. Twenty-five patients (80.6%) achieved a complete response. At 2-years, OAS is 94.4% and DFS is 72.6%. T3 and residual after TUR are factors that adversely affects DFS. Conclusion Hypofractionated radiotherapy and gemcitabine as a radiosensitizer in elderly as organ preservation for TCC bladder cancer have acceptable toxicity profile with good response rate and disease-free survival, keeping salvage cystectomy for persistence or recurrence of invasive cancer. EP-1616 Outcomes Following Primary Radiochemotherapy in Patients with Localy Advanced Bladder Cancer I. Albitskiy 1 , T. Aro 2 , T. Charas 1 , G. Amiel 2 , R. Ben Yosef 1 1 rambam medical center, radiation oncology, Haifa, Israel 2 rambam medical center, urology, Haifa, Israel Purpose or Objective Radical cystectomy is the treatment of choice for locally advanced invasive bladder cancer. External beam irradiation in combination with chemotherapy following endoscopic resection of the tumor is considered an alternative treatment for selected patients with small tumor burden or with contraindication for surgery because of performance status and co-morbidities. The aim of this study is to report on the outcome of patients