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employed to assess the efficacy of SBRT and SBRT combined with chemotherapy. Results Two hundred and twenty-five patients were included with the median prescription dose and BED 10 was 35Gy and 59.5Gy, respectively. Three patients died within 3 months, which were precluded for analysis. After multivariate analysis, baseline visual analogue scale, treatment sequence of chemo-SBRT, BED 10 , CA19-9 response, post-treatment ESAS and BPI correlated with overall survival (OS) and the former five plus EQ-5D-5L were predictive of progression free survival (PFS). More patients (n=16, 43.2%) receiving SBRT alone had lower BPI scores than those with SBRT and chemotherapy (n=41, 22.2%) (P=0.007), while more patients (n=48, 25.9%) undergoing multimodality therapy had higher EQ-5D-5L scores than those with SBRT alone (n=1, 2.7%) (P=0.001). No significant difference of ESAS scores was found between these two groups (P=0.422). Irrespective of patient global changes, longer OS and PFS was found in patients with SBRT and chemotherapy than those with SBRT alone (OS: 8.9 months vs. 4.6 months, P<0.001) (PFS: 5.4 months vs. 2.0 months, P<0.001). Additionally, more patients (n=76, 41.1%) with SBRT and chemotherapy had CA19-9 response than those with SBRT alone (n=0, 0%) (P<0.001). After PSM, survival benefits were found in patients with SBRT and chemotherapy than those with SBRT alone (OS: 6.5 months vs. 4.6 months, P=0.042) (PFS: 2.8 months vs. 2.1 months, P=0.027), though more patients with SBRT alone had lower BPI and ESAS scores. Conclusion Although SBRT alone may be beneficial for symptom amelioration, SBRT combined with chemotherapy may provide survival benefits and be not inferior to SBRT alone in improvement of QoL. S. Tsuruoka 1 , M. Kataoka 2 , K. Makita 1 , H. Ishikawa 1 , N. Takada 1 , K. Nagasaki 1 , Y. Hamamoto 1 , T. Mochizuki 1 1 Graduate School of Medicine Ehime University, Radiology, Ehime, Japan 2 National Hospital Organization Shikoku Cancer Center, Radiation Oncology, Ehime, Japan Purpose or Objective The reports on the results of radiotherapy (RT) for stage I esophageal cancer is limited, and the efficacy of elective nodal irradiation (ENI) is still unclear. The purpose of this retrospective study is to evaluate the efficacy of ENI in stage I esophageal cancer treated with RT. Material and Methods From April 2006 to December 2014, 79 patients with stage I esophageal cancer were received RT in our institute. Two patients combined with stage IV hypopharyngeal carcinoma, three patients whose follow- up time was less than 6 months and two patients who failed to complete RT were excluded, and 72 patients were analyzed in this study. Sixty patients out of 72 (83.3%) were treated with concurrent chemoradiotherapy (CRT) (delivered median 60Gy (41.4 to 60Gy)) and 22 of 72 (30.6%) were with RT alone (delivered median 66Gy (60 to 70Gy)). Twenty patients (27.8%) were received RT with ENI. Endoscopic submucosal dissection was performed before RT in 12 patients. The primary outcomes were overall survival (OS) and disease-free survival (DFS). Results The median age was 68 years old (50 to 89). The male/female ratio was 64/8. The median follow-up was 54.7 months (2.5 to 126.5 months). The tumor histology was squamous cell carcinoma in all patients. The subsites of the primary tumors were upper/middle/lower thoracic portions/ abdominal portions in 11/50/9/2, respectively. Tumor invasion confined to the mucosa, submucosa and EP-1435 The role of elective nodal irradiation in radiotherapy for stage I esophageal cancer

muscularis propria was 13, 52 and 7, respectively. Three- year OS and DFS were 81.7% and 58.3%, respectively. Three-year OS were 89.7% and 78.7% in the patients with and without ENI, respectively. And 3-year/5-year DFS in patients with and without ENI were 75.0%/51.9% and 37.3%/31.8%, respectively. There was no significant difference for OS and DFS (p=0.68 and p=0.23, respectively). A total of 17 patients (23.6%) relapsed: 6 (8.3%) developed local, 11 (13.9%) developed regional (with/without ENI, 2/9; out/in-field, 10/1), 1 developed loco-regional and 1 developed lung metastasis. On univariate analysis for OS and DFS, ENI was not significant factor (p=0.69 and p=0.22, respectively), and Age, PS and treatment modalities (CRT vs RT alone) were significant factors for OS. On multivariate analysis, higher age (hazard ratio [HR] 1.06; 95% confident interval (CI) = 1.01-1.12; p=0.019,), and worse PS (HR 1.81; 95% CI = 1.04-2.93; p=0.038) were independently associated with worse OS. Conclusion This analysis suggested that ENI was not necessary for patients treated with RT for stage I esophageal cancer. A further prospective study to evaluate the role of ENI in stage I esophageal cancer is warranted. EP-1436 Impact of Complete Pathological Response to Neoadjuvant Chemoradiotherapy in Esophageal Cancer T. Soror 1,2 , G. Kho 2 , K. Zhao 3 , M. Ismail 4 , H. Badakhsh 2 1 National Cancer Institute, Radiation Oncology, Cairo, Egypt 2 Ernst von Bergmann Medical Center- Academic Teaching Hospital of Humboldt University Berlin Charité- Germany, Department of Clinical Radiation Oncology, Berlin, Germany 3 Fudan University Cancer Center, Radiation Oncology, - Shanghai-, China 4 Charité University Hospital, Thoracic surgery, Berlin, Germany Purpose or Objective Neoadjuvant chemoradiotherapy (CRT) followed by surgery improves the treatment outcome in patients with esophageal cancer, the pathological response is an important predictor in such patients. This work represents a single-center analysis. Material and Methods All patients treated with neoadjuvant chemoradiotherapy (CRT) followed by surgery between January 2002 and December 2013 were reviewed. The patients were categorized into two groups according to the pathological response following CRT; complete pathological response (pCR group) and non-complete pathological response (non-pCR group). Statistical significance level was established at p<0.05 and survival curves were estimated using the Kaplan-Meier method. Statistical analyses were performed using IBM SPSS Statistics for Windows, Version 22.0. (Armonk, NY: IBM Corp.).