ESTRO 36 Abstract Book

S391 ESTRO 36 _______________________________________________________________________________________________

0.77–0.89), p=0.036] and CTV_5220 [0.15 (range 0.02– 0.36) vs 0.43 (range 0.11–0.64), p=0.002]. CTV_5220 was incorrectly positioned in 5 submissions due to the contouring inaccuracies of GTV/CTV_6000. Other variations in the inclusion of the scar/seroma were seen where it was not fully encompassed axially (CTV_6000: 8 submissions, CTV_5220: 6 submissions), and wh ere CTV_6000 was extended beyond margins longitudinally to include it (5 submissions). In addition, some volumes were tapered where the anatomical planes were not followed lengthwise (CTV_6000: 5 submissions, CTV_5220: 13 submissions). There were five re-submissions after feedback, for which all target volumes had either acceptable, or no variation from the protocol (mean DSC GTV: 0.75, CTV_6000: 0.83, CTV_5220: 0.48). Conclusion High numbers of unacceptable variations from the trial protocol were seen in the first submission of the training case; the adherence to the protocol improved following individualised feedback. As the outlining of both CTVs is dependent on the accuracy of the reconstructed GTV in the post-operative setting, this should be done with particular care, with the aid of surgical reports and diagnostic imaging. PO-0743 Retransplantation of bony autografts sterilized by extracorporal high dose irradiation L. Saleh-Ebrahimi 1 , A. Klein 2 , Y. Bakhshai 2 , F. Roeder 1,3 , A. Baur-Melnyk 4 , T. Knösel 5 , L.H. Lindner 6 , V. Jansson 2 , H.R. Dürr 2 1 LMU Munich, Department of Radiation Oncology, Munich, Germany 2 LMU Munich, Department of Orthopedics, Munich, Germany 3 German Cancer Research Center DKFZ, Department of Molecular Radiation Oncology, Heidelberg, Germany 4 LMU Munich, Department of Radiology, Munich, Germany 5 LMU Munich, Department of Pathology, Munich, Germany 6 LMU Munich, Department of Internal Medicine, Munich, Germany Purpose or Objective Limb-sparing resection of bone tumors requires reconstruction of the bony defect. Retransplantation of the resected bone after sterilisation might be an alternative to prothetic implants especially in cases with diaphyseal defects. Here we report our experience with this technique using extracorporal high dose irradiation to sterilize the resected bone. Material and Methods Extracorporal irradiation and retransplantation was used in 20 patients (21 lesions) between 2005 and 2015. 13 patients were male and median age was 37 years (10-83) with 4 patients <18 years. Main histologies were Ewing sarcoma (7 pts), Osteosarcoma (5) and metastasis (5). Lesions were located mainly in the lower limb (femur n=12, tibia n=6). After resection and curettage, the tumor-bearing bone was packed into a double sterile bag and transported to the radiation oncology department. To minimize any built-up effect, the bag was wrapped with flap material and placed beneath the LINAC with the lowest possible distance to the head, usually on a tray in the accessory slot. After irradiation with 300 Gy in ap/pa technique, the bone was brought back to the operation room and retransplanted. Results Median follow up was 33 months (6-129) in the entire cohort and 39 months in survivors. Retransplantation was possible in all patients. An additional fibula augmentation was used in 14 lesions. Surgical revisions (median n=2, range 1-8) were needed in 12 lesions (57%) due to complications or pseudoarthrosis. Complete integration of

the irradiated autograft was finally achieved in 17 of 19 possible lesions (89%). One patient failed with active pseudoarthrosis and in one patient a prothetic implant was needed secondarily due to a fractured pseudoarthrosis. In two patients with retransplantation of the whole irradiated calcaneus, integration was formally not possible. Median time to complete integration was 10 months (4-35 months). Local control inside the graft and in the affected limb was achieved in 100% and 95% of the patients, respectively. One patient developed recurrence outside the replanted graft, probably due to seeding because of fracture hematoma. Four patients have died, resulting in a 5-year overall survival of 68 %. Conclusion High dose extracorporal irradiation is an effective and safe method to sterilize bony autografts during a retransplantation procedure. Local control is achieved in 95%-100%. Complications with the need for surgical revisions occur frequently resulting in a prolonged healing process in more than half of the patients. However, successful integration of the sterilized autografts is finally achieved in the vast majority (roughly 90%). Retransplantation after extracorporal irradiation seems to be a very promising alternative to prothetic implants especially in the treatment of diaphyseal or metadiasphyseal lesions. PO-0744 Brachytherapy and external beam radiation therapy after re-excision surgery in soft tissue sarcomas A. Cortesi 1,2 , A. Arcelli 1,3 , L. Giaccherini 1 , A. Galuppi 1 , V. Panni 1 , A. Zamagni 1 , S. Bisello 1 , F. Romani 4 , G. Bianchi 5 , S. Campagnoni 5 , M. Gambarotti 6 , G. Ghigi 2 , S. Micheletti 7 , G. Macchia 8 , F. Deodato 8 , S. Cilla 9 , G.P. Frezza 3 , A.G. Morganti 1 , S. Cammelli 1 1 University of Bologna, Radiation Oncology Center- Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy 2 Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori IRST- IRCCS, Radiotherapy Department, Ravenna, Italy 3 Ospedale Bellaria, Radiotherapy Department, Bologna, Italy 4 S. Orsola-Malpighi Hospital- University of Bologna, Medical Physic Unit, Bologna, Italy 5 Rizzoli Institute, Department of Orthopaedic Oncology, Bologna, Italy 6 Istituto Ortopedico Rizzoli, Department of Pathology, Bologna, Italy 7 Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori IRST- IRCCS, Radiotherapy Department, Meldola, Italy 8 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Radiotherapy Unit, Campobasso, Italy 9 Fondazione di Ricerca e Cura “Giovanni Paolo II”, Medical Physics Unit, Campobasso, Italy Purpose or Objective To evaluate outcomes in patients with primary high grade soft tissue sarcomas (STS), treated with perioperative brachytherapy (BRT) and adjuvant external beam radiation therapy (EBRT) after re-excision of the tumor bed, post unplanned surgery. Material and Methods The primary aim of this retrospective study was to analyse local control (LC). Secondary objective were metastasis- free survival (MFS), diseases-free survival (DFS) and overall survival (OS) in a large patient population. BRT delivered dose was 20 Gy (15-22 Gy) using Low Dose-Rate or Pulsed Dose-Rate technique. EBRT was delivered with 3D-technique using multiple beams; the median prescribed dose was 46 Gy to the PTV (range 40-60 Gy), conventionally fractionated. Univariate analysis was estimated according to Kaplan-Meier method and log-rank test.