ESTRO 38 Abstract book

S865 ESTRO 38

PORT should be performed immediately after surgery as initial treatment of choice, irrespective of margin status and tumor size. β-catenin staining intensity of IHC might correlate with local recurrence. Further investigations to validate its prognostic value are needed. EP-1604 Feasibility of preoperative radiotherapy in localized sarcoma of the limb:a single center experience B. Durand 1 , G. Decanter 2 , M. Jafari 2 , W. Tessier 2 , Y. Robin 3 , A. Renaud 4 , M. Ben Haj Amor 4 , L. Basson 5 , D. Pannier 6 , T. Ryckewaert 6 , N. Penel 6 , A. Córdoba Largo 7 1 Centre Oscar Lambret, Department of Radiotherapy, Lille, France ; 2 Centre Oscar Lambret, Surgery Department, Lille, France ; 3 Centre Oscar Lambret, Pathology department, Lille, France ; 4 Centre Oscar Lambret, Imaging department, Lille, France ; 5 Centre Oscar Lambret, Academic Radiation Department, Lille, France ; 6 Centre Oscar Lambret, Medical Oncology department, Lille, France ; 7 Centre Oscar Lambret, Department of Radiation Oncology, Lille, France Purpose or Objective To report feasibility and first clinical and toxicity data from a retrospective series of patients treated with the association of preoperative radiotherapy and radical surgery for a localized sarcoma in the limbs in our referenced center. Material and Methods All patients with soft tissue sarcoma of the limbs treated consecutively in our institution by preoperative radiotherapy and surgery combination. The combined treatment of preoperative radiotherapy and surgery was decided in a multidisciplinary consultation meeting depending on the histological type, the relationship of the tumor to the blood vessels and the size of the tumor. Principal objective: Feasibility of pre-operative radiotherapy followed by surgery at 4-6 weeks; Secondary: Resection quality (R0, R1, R2), Post-operative complication rate, Survival without local recurrence, Histological response (necrosis rate) to preoperative radiotherapy. Results 31 patients were enrolled on a 4-year period. In 25 patients (80.6%) tumor was in lower limb. Vascular relation < 5mm on MRI was observed in 19 patients (61.3%), 27 patients (87.1%) were classed T2b and the median largest axis was initially 12 cm (1.7-30), the median depth was 7cm. Initial biopsy was performed in our center in 22 patients (71%). Histology based on biopsy was: sarcoma indifferenced in 11 patients (35.5%), adipocytic tumor in 10 patients (32.3%) and autre in 10 patients (32.3%). Preoperative radiotherapy delivered 45 to 50,4 Gy at 1,8 Gy fractions; IMRT for 26 patients (83,9%) and 3D-CRT for 5 (16.1%) patients. All patients were operated with a conservative intent with 49 days (24-83) median after the end of the radiotherapy. In 28 patients, (90.3%) we performed image, MRI in 25 (89.3%) patients or CT (9.7%) in 3 patients, before surgery. In 25 patients (80.6%) surgery was R0 and in the other six patients (19.4%) was R1. Histology after surgery was: sarcoma indifferenced in 13 patients (41.9%), adipocytic tumor in 9 patients (29%) and autre in 9 patients (29%). Flap was needed in 11 patients (35.5%), 5 (16.1%) immediately and 6 (19.4%) remote flap because delayed healing. Bone fracture was observed in 3 patients (9.7%). Three patients presented chronic pain (1 patient grade 1 and 2 patients grade 2). At the end of our median follow-up of 18 months, there were 6 relapses, 5 metastatic and 1 local), 2 of them died of the disease evolution. Conclusion Preoperative radiotherapy in locally advanced sarcoma of the limb is feasible, when achieved in a reference center, with a satisfactory early clinical and toxicity data.

EP-1605 Adjuvant RT for soft tissue sarcomas: volumetric modulated arc therapy vs 3D conformal radiotherapy L. Di Brina 1 , P. Navarria 1 , G.R. D'Agostino 1 , F. De Rose 1 , C. Iftode 1 , E. Clerici 1 , F. Lobefalo 1 , A. Bertuzzi 2 , V. Quagliuolo 3 , M. Scorsetti 4 1 Humanitas Clinical and Research Center, Radiotherapy and Radiosurgery, Rozzano, Italy ; 2 Humanitas Clinical and Research Center, Medical Oncology, Rozzano, Italy ; 3 Humanitas Clinical and Research Center, Surgical Oncology, Rozzano, Italy ; 4 Humanitas University, Biomedical Sciences, Rozzano, Italy Purpose or Objective Soft tissue sarcomas (STS) represent rare tumors of mesenchymal origin, frequently detected to the extremities. Nowadays limb-sparing surgical resection followed by radiation therapy (RT) is considered the standard treatment in large, high-grade sarcomas. Recent RT technological advances allow to improve the tumor coverage with maximum sparing of normal tissues. Aim of this study is to assess the impact of VMAT compared with 3DCRT in patients with diagnosis of STS of the extremities and treated with surgery and adjuvant RT in terms of toxicity, local control (LC), disease free survival (DFS) and This analysis included patients with diagnosis of STS of the extremity treated with limb-sparing surgery and submitted to adjuvant RT for one or more of the following risk factors: deeply located tumors, grade II-III, maximum diameter larger than 5 cm and marginal surgical resection. From 2004 to 2010 plans were processed using 3DCRT. Starting from 2011 to 2016, all patients were treated with VMAT. Response was recorded with contrast-enhanced MRI and thoracic and abdominal CT scan every 3 months. Toxicity was evaluated with Common Terminology Criteria for Adverse Events (CTCAE) scale version 4.3. Results From 2005 to 2016, 109 patients were treated in our center and included in the analysis. Median age was 55 years (range 15-84 years) .The majority of patients had disease of the lower extremity (95 patients, 87%). The most frequent histotype was liposarcoma (57,7%). Fifty- three patients received chemotherapy (CT). Radical surgical resection was performed in 76% of patients, 24 patients received R1 resection and 2 patients R2. 3DCRT was performed in 38 cases and VMAT in 71 cases. The administered total dose was 66 Gy in 33 fractions. Median follow-up was 70 months for the entire cohort, 121 months for the 3DCRT group, 61 months for the VMAT group. Actuarial LC at 3 years were 83.0% in 3DCRT group and 92.7% for patients in VMAT group. Actuarial DFS at 3 years were 74.0 % and 79.2% for patients who underwent 3DCRT and VMAT respectively. Actuarial OS at 3 years were 70.0% for patients who underwent 3DCRT, and 79.2% for VMAT group. Grade 1-2 acute skin toxicity occurred in 58% of the patients in 3DCRT group and 48% of VMAT group. One patient in each group presented grade 3 acute skin toxicity. Late toxicity was recorded in 38 patients (35%): nine patients treated with 3DCRT had grade 1 toxicity while in VMAT group 17 patients and 1 patients had G1-G2 and grade 4 skin toxicity respectively. Between VMAT patients 4 of them had G1 joint toxicity. Only margins and grade were significant factors for LR after univariate analysis (p=0.002). The technique influenced significantly OS both at univariate and multivariate analysis (p=0.006). Conclusion The availability of modern RT technique permit a better conformity on the target with maximum sparing of normal tissue and acceptable side effects. Results on local control and survival of VMAT are encouraging. More perspective overall survival (OS). Material and Methods