ESTRO 37 Abstract book

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ESTRO 37

(only one isolated nodal recurrence), transferring into 1- and 2-year LRC rates of 60% and 45%. 10 patients developed distant metastases, resulting in 1- and 2-year DC rates of 81% and 72%. 43 patients deceased, transferring into 1- and-2 year OS rates of 46% and 26%. OS was significantly associated with T stage (1-year OS T1-3: 56% vs T4: 9%, p=0.002), UICC stage (1-year OS UICC I-IIIB: 56% vs IIIC/IV: 10%, p=0.03), comorbidity (1- year OS CS <=1: 51% vs CS >1: 33%, p=0.04), and treatment period (1-year OS prior 2008: 24% vs after 2008: 66%, p<0.001).Completion of >80% chemotherapy showed an improved overall survival (1-year LRC 56% vs 10%, p=0.002), neoadjuvant treatment and IMRT vs. 3-D RT showed a trend to improved survival. Conclusion Curative intent radio(chemo)therapy in elderly patients can be associated with high morbidity and mortality although outcome clearly improved over time. Patients should be selected carefully and monitored very closely during and especially after the end of treatment. EP-1446 Stereotactic Body Radiotherapy (SBRT) in patients with HCC in a multimodal treatment setting S. Gerum 1 , C. Heinz 1 , C. Belka 1 , P. Paprottka 2 , E. De Toni 3 , F. Roeder 1 1 University Hospital LMU Munich, Radiation Oncology, Munich, Germany 2 University Hospital LMU Munich, Radiology, Munich, Germany 3 University Hospital LMU Munich, Gastroenterology, Munich, Germany Purpose or Objective To report our experience with stereotactic body irradiation in primary liver cancer. Material and Methods We retrospectively analyzed 28 patients with hepatocellular carcinoma (HCC) who received SBRT to a total of 38 lesions (max 2 per patient) in our institution from 2011-2016. Median age was 63 years (range 46–83 yrs), 20 patients were male, 8 female. 25 of them had previous treatments (surgery, RFA, TACE or SIRT, median 2, range 0 to 8). Actually 13 patients received SBRT alone while 15 patients were treated by TACE and SBRT to the same lesion within 6 weeks. 5 patients additionally received RFA treatments to different lesions. The majority presented in good performance status (median KPS 90 %, range 60%-100%) mainly with moderately restricted liver function (cirrhosis Child A: 22, Child B: 5, Child C: 1). Immobilization included a vacuum pillow and the use of abdominal compression since 2014. Treatment planning was based on 4D-CT (contrast-enhanced since 2014, n=14) and rigid registration with diagnostic MRI images. Usually 1-3 fiducial markers were placed except in case with sufficient lipiodol enhancement for localization after TACE (n=10; 36%). Median ITV to PTV margin was 6 mm. Results Mean follow-up was 13 months (range 2 – 57). Fiducial placement was feasible without any severe complications. Dose and fractionation varied dependent on localization, size, motion and liver function. The most common schemes were 3x12.5Gy to the 65%-isodose (57%) and 5x8Gy/80% (23%). Median GTV volume on free- breathing CT was 12 ccm (0,9 – 204) and median PTV volume was 67 ccm (15 - 511). Local recurrence (in-field) was observed in 2 patients (7%) resulting in an estimated 1-year LC-rate of 92%. New hepatic lesions (out-field) occurred in 12 patients (43%) and 5 pts. (18%) developed

extrahepatic progression. 8 patients have died, resulting in an estimated 1-year overall survival of 65 %. Patients with poor liver function (Child B/C) had a significantly decreased 1-year overall survival (28%) compared to Child A patients (74%). 5 patients (18%) received liver transplantation after a median time of 6 months (range 1-8) from SBRT. In 4/5 patients no vital residual tumor was found in the explanted liver. Toxicity of the SBRT procedure was generally mild (grade 1: 6 pts., grade 2: 2 pts.). Conclusion SBRT with or without prior TACE is feasible and associated with excellent short term local control and low toxicity in patients with HCC. SBRT can be used as definitive or bridging treatment prior to planned liver transplantation. Patients with poor liver function have a significantly decreased 1-year OS. EP-1447 The impact of residual tumor in gastric cancer patients received adjuvant chemoradiation M.L. Zhou 1 , R. Hu 1 , W. Yang 1 , Y. Wang 1 , G.C. Li 1 , Z. Zhang 1 1 Fudan University Shanghai Cancer Center, Department of Radiation Oncology, Shanghai, China Purpose or Objective Residual disease after resections is a well-known adverse prognostic factor after gastric cancer surgery. However, the prognostic significance of an R1/R2 resection in gastric cancer patients who are treated with chemoradiotherapy (CRT) after the operation has been poorly studied. Therefore, the aim of this study was to evaluate the effect of an R1/R2 resection on survival in gastric cancer patients who were treated with CRT after surgery. Material and Methods Gastric cancer patients who had undergone a resection with curative intent followed by adjuvant CRT at our institute between 2004 and 2015 were included. CRT consisted of radiotherapy (45 Gy/25 fractions) combined with concurrent 5-fluorouracil , capecitabine or S-1. Results A total of 38 patients were identified and assigned into the non-R0 group, including 27 patients who had undergone an R1 resection and 11 patients who received an R2 resection. 190 patients who received an R0 resection were selected using propensity-score matching with a ratio of 1:5. The baseline characteristics including age, sex, tumor site, T- and N- stages were well balanced. Three-year recurrence-free survival (58.2 vs. 15.1%, p=0.00) and overall survival (69.4 vs. 39.0%, p=0.00) of patients in the R0 group were significantly better. In a multivariate analysis, pathologic T-, N-stage and residual disease (R0 vs. non-R0) were independent prognostic factors for survival. Conclusion A resection with residual disease was an independent adverse prognostic factor in gastric cancer patients who had undergone CRT after the operation. A R0 resection should be achieved as much as possible. EP-1448 Robotic SBRT on liver lesions in oligometastatic CRC patients: a single center experience M. Vernaleone 1 , P. Bonomo 1 , V. Di Cataldo 2 , L. Masi 2 , I. Desideri 1 , D. Greto 1 , G. Francolini 2 , L. Visani 1 , E. Olmetto 1 , F. Terziani 1 , L. Livi 1 1 Azienda Ospedaliera Universitaria Careggi, Radioterapia