ESTRO 38 Abstract book

S767 ESTRO 38

EP-1409 QoL for Gem and ABX plus SBRT versus Gem and S-1 plus SBRT in metastatic pancreatic cancer X. Zhu 1 , C. Yangsen 1 , Z. Xianzhi 1 , S. Yuxin 1 , J. Xiaoping 1 , Q. Shuiwang 1 , C. Fei 1 , J. Zhen 1 , F. Fang 1 , J. Zhen 1 , Z. Huojun 1 1 Changhai Hospital, Radiation Oncology, Shanghai, China Purpose or Objective Nearly 50% of patients had metastatic pancreatic cancer at initial diagnose. Therefore, priority may be given to quality of life, which required improvement of survival without simultaneously compromise of health-related quality of life (HRQOL) during treatment. Moreover, radiotherapy could be an option for amelioration of local symptoms in addition to potential abscopal effects, contributing to improvement of HRQOL. Hence, we sought to evaluate the HRQOL after SBRT and different chemotherapy regimens in the management of metastatic pancreatic cancer. Material and Methods Patients with biopsy-proven and radiographically metastatic pancreatic cancer were included and prospectively followed up from 2013 to 2017. Chemotherapy was delivered after SBRT with an interval of 3 weeks, which were required for 4 cycles. The regimens were gemcitabine plus nab-paclitaxel (GT group) or gemcitabine plus S-1 (GS group). The Chinese version of Brief Pain Inventory (BPI) and 5-level European quality of life 5-dimensions (EQ-5D-5L) were used in this study. Due to limited survival of patients with metastatic pancreatic cancer, questionnaires were completed before SBRT and right after the whole treatment. Patient-reported global changes and scores of questionnaires were assessed. To be simplified, all changes were stratified into “better”, “no change” and “worse” in the analysis. Data were analyzed with Spearman’s rank correlation, ordinal regression. Propensity score matched analysis were further performed to evaluate these two regimens. Results Seventy-five and eighty-nine patients received gemcitabine plus nab-paclitaxel and gemcitabine plus S-1, respectively. No differences of baseline characteristics were found between these two groups. No differences of BPI scores were found between pre- and post-treatment in each group, while only the post-treatment EQ-5D-5L score was higher than that at baseline in GS group (P<0.001). The response “better” of BPI was found in 15 and 38 patients in GT and GS group, respectively (P<0.001). On multinomial logistic regression, compared with GS group, the probability of GT group achieving “better” global change of BPI was 0.289 (P=0.015). The “better” change of EQ-5D-5L was found in 20 and 42 patients in GT and GS group, respectively (P<0.001). After multinomial analysis, compared with GS group, the probability of GT group gaining improvement of EQ-5D-5L was 0.334 (P=0.031). After propensity score matching analysis, more patients had improvement of BPI and EQ-5D-5L in GS group compared with GT group (n=24 vs. n=12, P=0.002; n=28 vs. n=16, P=0.002). No grade 3 or more radiation-induced toxicity occurred. More patients in GT group experienced grade 3 or more hematological and gastrointestinal toxicity than those in GS group (n=25 vs. n=16, P=0.024; n=17 vs. n=10, P=0.049). Conclusion GS may achieve better HRQOL than GT. Therefore, GS may be an alternative of GT for metastatic pancreatic cancer, especially for Asians. EP-1410 PET compared to CT in target delineation for SBRT of pancreas adenocarcinoma. C. De la Pinta Alonso 1 , J.D. García 2 , D. Sevillano 2 , A. Martínez-Lorca 3 , R. García 4 , M. Martín 1 , M. Martín 1 , R. Hernanz 1 , E. Fernández-Lizarbe 1 , T. Muñóz 1 , J.A. Domínguez 1 , J.F. Crespo 5 , C. Vallejo 1 , A. Hervás 1 , F. López 1 , S. Sancho 1

1 Ramon y Cajal Hospital, Radiation Oncology, Madrid, Spain ; 2 Ramon y Cajal Hospital, Medical Physics, Madrid, Spain ; 3 Ramon y Cajal Hospital, Nuclear Medicine Department, Madrid, Spain ; 4 Ramon y Cajal Hospital, Radiology Department, Madrid, Spain ; 5 Ramon y Cajal Hospital, Nursery Department, Madrid, Spain Purpose or Objective In SBRT quality control of target delineation pancreatic tumors is essential to deliver adequate doses of radiation to the primary tumor while preserving adjacent healthy organs. The purposes of this study was to evaluate the variability in contouring of these tumors in our center and our hypothesis is that PET allows better visualization of pancreatic tumours and will optimize the accuracy of tumor delineation for SBRT compared with CT only. Material and Methods A planning CT and PET/CT were performed in all patients. Gross tumor volume (GTV) in both CT and PET/CT were delineated. 8 physicians of Radiation Oncology Department performed the contours. Pancreatic locations included bed surgery recurrence, pancreatic body (2p) and pancreatic-head. The cases show different difficulty: low acquisition contrast, previously treated with chemotherapy or low SUV in PET/CT. In both CT and PET, the GTV volumes, conformity index (CI) and distance between the centers of mass (dCOM) were compared. Results Four patients were included. The GTV volume as defined on CT was in all cases larger or at least as large as the GTV volume on PET. The median GTV volume on PET was 7,1 mL (range,1,7–14,9 mL), compared to 12,5 mL on CT (range 5–18,6 mL). Contouring of pancreatic adenocarcinoma on CT resulted in non-statistically significant larger lesions (mean increase 5,46mL) compared with PET (p=0.254). Variability between observers in CT was minor that PET (17,14 vs 23,45mL). Overlap ratio has not showed differences between CT and PET. Conclusion PET and TC seems to represent extend of the GTV in pancreatic tumors accurately. Contouring based on CT- only could result in an overestimation of the actual tumor volume, which may cause overdosage of the GTV in SBRT treatment plans by this combining CT and PET could be help in contouring. The interobserver variability in target delineation of pancreatic tumors GTV in this study is noteworthy. We consider need multi-institution studies involving abdominal SBRT require appropriate quality assurance programs for target delineation. EP-1411 What is the best imaging study to contouring liver metastases in SBRT? C. De la Pinta Alonso 1 , J.D. García 2 , D. Sevillano 2 , R. García 3 , A. Martínez-Lorca 4 , M. Martín 1 , E. Fernández- Lizarbe 1 , M. Martín 1 , J.A. Domínguez 1 , R. Hernanz 1 , T. Muñóz 1 , S. Sancho 1 1 Hospital Ramon y Cajal, Radiation Oncology, Madrid, Spain ; 2 Hospital Ramon y Cajal, Medical Physics, Madrid, Spain ; 3 Hospital Ramon y Cajal, Radiology Department, Madrid, Spain ; 4 Hospital Ramon y Cajal, Nuclear Medicine, Madrid, Spain Purpose or Objective In SBRT tumor delineation is essential to deliver adequate doses of radiation while preserving adjacent healthy organs. Defining liver metastases gross tumor volume (GTV) requires multimodal imaging, acquired in different perfusion phases. Most liver metastases can be imaged in the portal venous phase. The purposes of this study was to evaluate the variability in contouring of these tumors in our center and compare three studies: CT, MRI and PET Material and Methods Anonymous, multiphasic-CT, MRI and PET/CT obtained from five patients (6 lesions) with liver metastases were