ESTRO 37 Abstract book

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ESTRO 37

resection. Postoperative radiotherapy (PORT) had been carried out to improve local control, but nowadays it has been reluctant to use due to its higher complication risk. So far, most of the studies investigating PORT are based on the old RT technique. We investigated the efficacy of PORT using modern RT technique in patients treated with retroperitoneal soft tissue sarcoma. Material and Methods A total of 80 patients who underwent surgical resection for non-metastatic primary retroperitoneal soft tissue sarcoma at Yonsei Cancer Center between 1993 and 2015 were retrospectively reviewed. The most common histologic subtype was liposarcoma (52.5%) followed by leiomyosarcoma (22.5%), undifferentiated pleomorphic sarcoma (11.2%) and others (13.8%). Resection margin status was R0 in 45 patients (56.2%), R1 in 24 patients (30%), and R2 in 11 patients (13.8%). PORT was delivered in 38 patients (47.5%) with a median dose of 54 Gy in 1.8 Gy per fraction using 3-dimensional RT or intensity modulated RT. Adjuvant chemotherapy was performed in 23 patients (28.8%) with a regimen of adriamycin/ifosfamide. The effect of PORT on local failure-free survival (LFFS), overall survival (OS) as well as RT-related toxicities was investigated. Results The median follow-up was 37.1 months (range, 5.8-207.9 months) for entire patients. The median LFFS and OS were 56.3 and 146.9 months for all patients, respectively. Treatment failure was occurred in 47/80 patients (58.8%); local recurrence in 33 patients (41.3%), distant metastasis in 8 patients (10%), and both in 6 patients (7.5%). While PORT was performed more frequently in patients who underwent R1 or R2 resection (P = 0.039), there were no significant differences in other clinical characteristics between PORT group and no-PORT group. The LFFS was significantly better in PORT group; the 5-year LFFS rate was 74.2% for PORT group and 24.3% for no-PORT group (P < 0.001). In multivariate analysis, the use of PORT were the only independent prognostic factor for LFFS (P=0.002). However, there was no significant correlation between RT dose and the LFFS. OS showed no significant difference between two groups. Grade ≤ 2 acute toxicities were observed in 63% of patients, but no acute toxicity of grade > 3 was observed. Only 1 patient who received 65 Gy developed a neuropathy as a late complication. Conclusion PORT markedly reduced a local recurrence in retroperitoneal sarcoma patients. Using modern RT technique, there was no severe RT-related complication. Optimal RT technique in terms of RT dose and target volume should be further investigated.

and prognostic factor were reviewed. Survival outcomes were calculated using Kaplan-Meier method and prognostic factors were evaluated by Cox regression analysis. Results Median follow up was 33 months (mean 51, range, 2.5- 179.2). Median age was 9.1 years (range, 0.4-74.1) and twenty patients were diagnosed with de novo stage IV disease. Fifteen patients had favorble primary site and embryonal type was the most common pathological type with 31 (50%) cases. Thirty eight patients underwent surgery and sixty patients received chemotherapy. The most commonly used chemotherapy regimen was vincristine, Adriamycin, and cyclophosphamide (VAC). Excluding stage IV patients, median radiation dose was 45.0 Gy (Mean 44.6, range, 14.0-60.0). While median overall survival (OS) was not reached, 1-year OS was 93.5 percent and 3-year OS was 63.6 percent. Median progression free survival (PFS) was 18.7 months with 1- year PFS of 65.2 percent and 3-year PFS of 41.8 percent. Univariate analysis revealed age (p=0.025), site (p=0.03), TNM stage (p<0.001), and Intergroup rhabdomyosarcoma study clinical group (IRSG) (p=0.001) as significant prognostic factors. In multivariate analysis, age (p=0.002) and TNM stage (p<0.001) were statistically significant. After excluding stage IV patients who had had worst outcome and categorizing patients into four groups according to age and primary site, patients who were younger than 10 with favorable primary site had significantly better survival outcome. For futher investigation on primary site, we divided patients to five groups according to their primary sites as follows: non- parameningeal head and neck, parameningeal, genitourinary, extremity, and others, defined as the rest part of body such as retroperitoneum. 3-year OS was 90.0 percent in non-parameningeal head and neck patients, 57.1 percent in parameningeal patients, 87.1 percent in genitourinary subgroup, 30.0 percent in extremity and 45.5 percent in “others” subgroup. Respective 3-year PFS was 88.9 percent, 35.7 percent, 37.4 percent, 20.0 percent and 18.2 percent. Conclusion This study showed multimodality treatment including radiotherapy could result in acceptable survival outcomes especially in young patients whose primary sites are non- parameningeal head and neck or genitourinary. However, treatment strategies should be further improved to achieve better survival in unfavorable groups. EP-1633 IOERT in primary retroperitoneal sarcoma: a retrospective single center analysis of 69 cases F. Roeder 1 , I. Alldinger 2 , M. Uhl 3 , L. Saleh-Ebrahimi 1 , S. Schimmack 4 , G. Mechtersheimer 5 , M. Büchler 4 , J. Debus 3 , R. Krempien 6 , A. Ulrich 4 1 University Hospital LMU Munich, Radiation Oncology, Munich, Germany 2 CPZ Düsseldorf, Surgery, Düsseldorf, Germany 3 University of Heidelberg, Radiation Oncology, Heidelberg, Germany 4 University of Heidelberg, Surgery, Heidelberg, Germany 5 University of Heidelberg, Pathology, Heidelberg, Germany 6 Helios Clinic Berlin-Buch, Radiation Oncology, Berlin- Buch, Germany Purpose or Objective To report our experience with surgery and intraoperative electron radiation therapy (IOERT) with or without

EP-1632 Clinical Outcome after Multimodality Approach including Radiotherapy in Rhabdomyosarcoma J.J.B. Lee 1 , S.H. Choi 1 , H.I. Yoon 1 , C.O. Suh 1 1 Yonsei Cancer Center, Deparment of Radiation Oncology, Seoul, Korea Republic of

Purpose or Objective To report Yonsei Cancer Center’s experience in treating rhabdomyosarcoma and evaluate treatment outcome and prognostic factors in subgroups. Material and Methods Sixty-two patients who received multimodal treatment including radiotherapy at the Yonsei Cancer Center from March, 2000 to November, 2015 were included. Clinical and treatment characteristics, pathologic features