Abstract Book

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ESTRO 37

0.1cc of oesophagus, spinal cord and small bowel on all occasions. P_ HYB did not meet lung V5Gy for any plan (88.2-99.4%), whereas P_ TO met in each case (68.3- 74.8%). P_ HYB met heart V35Gy on 5 occasions (25.2- 37.3%), however P_ TO met in all plans (24.6-35.0%). In two patients the dose to 0.1cc of the stomach failed for P_ HYB (0-51Gy), however this constraint passed on all occasions for P_ TO (0-43.3Gy). Reductions in OAR doses were observed when using the P_ TO plan in comparison to plans calculated without Trade-Offs. Utilising this new calculation method allowed all patients to have a clinically acceptable radical plan. Conclusion Trade-Offs planning provides improvements in OAR sparing when compared with hybrid IMRT/VMAT alone. The coverage of the PTV was comparable. The addition of multi criteria optimization provides improvements in plan quality that meet all pre-defined clinical objectives. EP-1409 Changes in pulmonary-function-test and toxicity evaluation after SBRT in early-stage NSCLC C. Cigarral García 1 , A. Matías Pérez 1 , J. Ramos González 2 , M. Saez Beltrán 3 , B. Cigarral García 4 , O. Alonso Rodríguez 1 , P. Soria Carreras 1 , M.T. Gómez Hernández 5 , L.A. Pérez Romasanta 1 1 Hospital Clínico Universitario de Salamanca, Radiation Oncology Department, Salamanca, Spain 2 Hospital Clínico Universitario de Salamanca, Pneumology Department, Salamanca, Spain 3 Hospital Clínico Universitario de Salamanca, Medical Physics Department, Salamanca, Spain 4 Hospital Clínico Universitario de Salamanca, Medical Oncology Department, Salamanca, Spain 5 Hospital Clínico Universitario de Salamanca, Thoracic Surgery Department, Salamanca, Spain Purpose or Objective Stereotactic body radiation therapy (SBRT) is the standard of care for patients with inoperable early-stage non-small cell lung cancer (NSCLC) or for those who refuse surgery. Most of these patients have advanced age and have different comorbidities such as moderate- severe chronic obstructive pulmonary disease (COPD) or vascular disease. The objective is to evaluate pulmonary- function-test (PFTs) changes and toxicity after lung SBRT. Material and Methods From June-2012 to October-2016, seventy-two patients with early-stage NSCLC were prospectively included in the study. Mean age was 72 years old (range 48–87). PFTs included forced expiratory vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and carbon monoxide diffusion capacity (DLCO c ) by the single-breath method. These parameters were measured at baseline and evaluated 1.5-months after SBRT and annually thereafter. Toxicity assessment was performed during and after SBRT according to CTCAE v4.0. Statistical analysis was performed with IBM® SPSS Statistics V.23.0 software. Results Median follow-up was 24 months (range 10-62). Asthenia Grade (G) 1-2 was the most common acute toxicity (19 patients [27%]). Acute radiation-induced pneumonitis G3 ocurred in 3 cases (4%) and was not increased among patients with lower PFTs. Chronic toxicity G1 was reported in 20 patients (27%), being radiation-induced pneumonitis the most common type (17 patients [85%]). Chronic toxicity G3 was observed in 4% of patients. A large variability of pretreatment PFTs was observed: median FEV1, FVC and DLCO c was 1.63L (range 0.48- 3.42), 2.55L (range 0.93-5.52) and 63.71% (range 19.4- 135.5%) respectively. No significant decline in FEV1 or FVC was observed during follow-up. DLCO c worsened significantly from baseline to 1.5-months after SBRT (67.72% vs 62.71%; p=.016) and from baseline to 12-

months after SBRT (69.96% vs 62.41%; p=.048) but with no significant changes at 24 and 36-months after SBRT. Conclusion Despite the significant decrease in DLCO c at 1.5-months and 12-months after-SBRT and the downward trend at 24 and 36 months, there was no significant long-term lung toxicity in a population with important basal COPD disease. According to previous reports, lower PFTs were no related to a high rate of respiratory events. SBRT is a well-tolerated and safe treatment even among a population with poor baseline lung function for inoperable patients with comorbid early NSCLC.

Electronic Poster: Clinical track: Upper GI (oesophagus, stomach, pancreas, liver)

EP-1410 Comparison of neoadjuvant chemoradiation with carboplatin/paclitaxel or CDDP/5-FU for esophageal SCC S. Münch 1 , S. Pigorsch 1 , M. Feith 2 , J. Slotta-Huspenina 3 , W. Weichert 3 , H. Friess 2 , S. Combs 1 , D. Habermehl 1 1 Klinikum rechts der Isar- Technical University of Munich, Radiation Oncology, Munich, Germany 2 Klinikum rechts der Isar- Technical University of Munich, Surgery, Munich, Germany 3 Klinikum rechts der Isar- Technical University of Munich, Pathology, Munich, Germany Purpose or Objective Neoadjuvant chemoradiation (nCRT) is the treatment of choice for patients with locally advanced squamous cell carcinoma of the esophagus (SCC). Today radiation oncologists can chose between to different therapy regimes including chemoradiation with cisplatin and 5- fluoruracil (CDDP/5FU) and chemoradiation analogue to the CROSS-regime with carboplatin and paclitaxel (Carb/TAX). However, there is a lack of studies comparing these regimes, especially for the subgroup of patients with SCC. In this study, we want to compare nCRT with CDDP/5FU and nCRT with Carb/TAX for patients with locally advanced SCC. Material and Methods We retrospectively compared 20 patients who were scheduled for nCRT with a total dose of 41.4 Gy (daily dose of 1.8 Gy) and weekly chemotherapy with carboplatin (Area under the curve 2) and Paclitaxel (50mg per square meter of body-surface area) according to the CROSS-regime to 31 patients who were scheduled for nCRT with a total radiation dose of 45 Gy (daily dose of 1.8 Gy) and a simultaneous chemotherapy with cisplatin (20mg/m²/d) and 5-fluoruracil (500mg/m²/d) on day 1-5 and 29-33. For the per-protocol analysis, per protocol treatment was defined as either complete radiation with 41.4 Gy and at least three cycles of Carb/TAX and subsequent surgery or complete radiation with 45 Gy and at least one complete cycle of CDDP/5FU with subsequent surgery. Results 51 patients (31 patients treated with CDDP/5FU and 20 patients treated with Carb/TAX) were evaluated for the ITT analysis and 44 patients (26 patients treated with CDDP/5FU and 18 patients treated with Carb/TAX) were evaluated for the PP analysis. No significant differences were seen for baseline and tumor characteristics like age, sex, TNM-stage, grading and tumor extension between patients treated with Carb/TAX and patients treated with CDDP/5FU. The most common tumor regression grade after neoadjuvant treatment was grade I as classified by Becker et al., which was observed in 84% and 79% of patients. No significant differences in tumor regression grades were seen between regimens. Postoperative insufficiency of the anastomosis was seen