Abstract Book

S880

ESTRO 37

Results From February 2007 to February 2017 a total of 35 patients with 58 lesions were included in our analysis. Leiomyosarcoma (41%) and synovial sarcoma (27%) were the most represented histologies. Five patients (15%) were identified with LM at the diagnosis. For the remaining 30 patients, LM appeared with a median time of 51 months (range 6-311 months). Median follow-up time from initial diagnosis was 87 months (5-251 months) and from SBRT was 31 months (2-92 months). Grade I–II late toxicity was recorded in 19 (54%) patients and it was diagnosed on CT scan at 9 and 12 months. No severe toxicity (grades III-IV) was observed both in acute and late setting. No patients required hospitalization. The actuarial 5-years local control rate (from SBRT treatment) was 96%. Overall survival at 2- and 5-years was 70% and 63.8%, respectively. At last follow-up 22 patients (62.9%) were alive. Conclusion According to our results, SBRT can be considered an effective and safe approach for lung metastasis in oligometastatic patients affected by STS. EP-1636 Role of preoperative radiotherapy in rare retroperitoneal sarcoma P. Navarria 1 , L. Di Brina 1 , E. Clerici 1 , C. Franzese 1 , G. D'Agostino 1 , T. Comito 1 , G. Carta 1 , A. Bertuzzi 2 , V. Quagliuolo 3 , M. Scorsetti 4 1 Humanitas Clinical and Research Center, Radiotherapy and Radiosurgery Department, Via Manzoni 56- 20089 Rozzano – Milan, Italy 2 Humanitas Clinical and Research Center, Medical Oncology Department, Via Manzoni 56- 20089 Rozzano – Milan, Italy 3 Humanitas Clinical and Research Center, Surgical Oncology Department, Via Manzoni 56- 20089 Rozzano – Milan, Italy 4 Humanitas University Department of Biomedical Sciences, Department of Biomedical Sciences, Via Manzoni 113- 20089 Rozzano –Milano, Italy Purpose or Objective Retroperitoneal sarcomas (RPS) are rare tumors and surgery is the standard treatment. Improved local control could be reached through a complete en bloc resection. RPS are usually characterized by an high rate of locoregional and/or distant failure but the main cause of death is represented by local recurrence (LR). For this reason, the use of radiation therapy (RT) for RPS increased over the past decades but no evidences are available about the optimal treatment. The aim of the present evaluation was to analyze the incidence of toxicities and perioperative morbidities in patients who underwent preoperative RT more or less with concurrent chemotherapy (CT). Local, distant failure and overall survival were assessed as well. Material and Methods All patients with histologically proven localized adult type soft tissue sarcoma (STS) of the retroperitoneum or pelvis, any histological grading, with largest diameter > 5 cm, no evidence of distant metastases (DM), received neoadjuvant treatment. Three cycles of CT with high- dose ifosfamide were administered concomitantly. A total dose of 50.4 Gy in 28 fractions was erogated to all the patients. Surgery was scheduled 4–6 weeks after the end of RT. Patients continued to be followed with thorax- abdomen CT scan performed every 4 months for the first 2 years, then every 6 months for the following 3 years, and yearly thereafter.

histology (61%). Lesions were grade 2 in 34% and grade 3 in 66%. Surgery resulted in gross complete resection in 94%, but only 19% had microscopic negative margins despite multivisceral resections in 58%. All patients had IOERT with a median dose of 15 Gy, 53 patients (64%) received additional perioperative EBRT (23% preop., 77% postop.) with a median dose of 45 Gy. Results Median follow-up for the entire cohort was 35 months and 43 months in surviving patients. Estimated 5-year-LC was only 35%. In univariate analysis, LC was significantly associated with UICC stage while only trends were present for grading, T stage and addition of EBRT. In multivariate analysis, only grading (5yr-LC G2 59% vs G3 22%) was found to be a significant factor regarding LC. Estimated 5-year OS was 48%. In univariate analysis, OS was significantly associated with grading and resection margin. Interestingly, only the achievement of gross total resection (GTR) was beneficial (5yr-OS GTR 55% vs no GTR 0%), while microscopic margin status (R0 vs R1) did not influence OS significantly. In multivariate Analysis,GTR remained the only significant factor for OS. Conclusion Outcome of recurrent high grade RPS was clearly worse compared to primary cases even after combination of surgery, IORT and EBRT. Reasonable efforts should be made already during primary treatment to prevent the onset of local recurrences. Prognostic factors may differ from primary cases and should be transferred with caution. GTR remained the only factor with significant impact on OS in multivariate analysis. EP-1635 Stereotactic body radiation therapy for lung metastases from soft tissue sarcoma: long term results L. Di Brina 1 , P. Navarria 1 , F. De Rose 1 , D. Franceschini 1 , C. Iftode 1 , A. Tozzi 1 , A. Marrari 2 , V. Quagliuolo 3 , M. Scorsetti 4 1 Humanitas Clinical and Research Center, Radiotherapy and Radiosurgery Department, Rozzano Milan, Italy 2 Humanitas Clinical and Research Center, Medical Oncology Department, Rozzano Milan, Italy 3 Humanitas Clinical and Research Center, Surgical Oncology Department, Rozzano Milan, Italy 4 Humanitas University, Department of Biomedical Sciences, Rozzano – Milan, Italy Purpose or Objective Patients with lung metastases (LM) from soft-tissue sarcomas (STS) have been treated with surgery and/or chemotherapy in the last decades. With the improvement of the radiation therapy (RT) techniques, stereotactic body radiation therapy (SBRT) has been included in the management of metastatic disease. With the aim to evaluate the role of SBRT in patients with LM from STS we retrospectively review the medical records of the patients treated at our institution Material and Methods Patients were treated with SBRT if in good performance status (ECOG 1-2), unsuitable for surgical resection, with controlled primary tumor. The number of lung metastases for every patient was ⩽ 4. In a risk adaptive scheme, the dose prescription was: 30Gy/1fr, 60Gy/3fr, 60Gy/8fr and 48Gy/4fr. All treatments were delivered with Volumetric Modulated Arc Therapy (VMAT). A thoracic and abdominal CT scan was performed every 3 months after SBRT to assess the clinical outcome. Toxicity was reported according to Common Terminology Criteria for Adverse Events (CTCAE) scale version 4.0.