ESTRO 2020 Abstract Book

S560 ESTRO 2020

Figure 1: overall survival for all patients and for patients undergoing surgery (borderline tumors) or without surgery (unresectable tumors) Conclusion The use of IFRT did not cause a significant amount of ENF, besides presenting low gastro-intestinal morbidity, of special importance for borderline patients who are candidates for surgery. The predominant failure pattern was distant metastases. PO-1054 Hypofractionated radiotherapy for unresectable esophagus-gastric carcinoma in elderly patients F. Lopez Campos 1 , M. Martín Martín 2 , L. Pelari 2 , E. Carrasco 3 , M. Martín 2 , J.A. Domínguez 2 , S. Sancho 2 1 Hospital Ramon y Cajal, Radiation Oncology, Madrid, Spain ; 2 Hospital Ramón y Cajal, Radiation Oncology, Madrid, Spain ; 3 Hospital Gómez Ulla, Radiation Oncology, Madrid, Spain Purpose or Objective A moderately hypofractionated radiotherapy schedule for unresectable esophagus-gastric carcinoma in elderly patients was prospectively evaluated in terms of efficacy, palliation of cancer-related symptoms and toxicities. Material and Methods Patients with clinically unresectable tumors of the esophagogastric junction or gastric adenocarcinoma who were not candidates for treatment with chemotherapy were enrolled in this study. The radiation dose was 37,5Gy/15 fractions (BED 42,19Gy) administered with a three-dimensional conformal radiation technique. The primary endpoint was palliation of cancer-related symptoms. Secondary endpoints included local control and toxicity. Palliation of cancer-related symptoms and toxicity were prospectively evaluated according to CTCAEv4 criteria. Results From August 2015 to March 2019, 18 patients were treated by the reported schedule. Median age was 85 (79-93). Cancer stage were: 28% stage IIB, 16% stage IIIA, 22% stage IIIB and 33% stage IIIC. All patients were able to complete the entire hypofractionated radiotherapy schedule. With a median follow up of 19 months (7-26) local control was 89% and palliation of cancer-related symptoms was 100%. According to toxicity, acute gastrointestinal toxicity grade I occurred in 6 patients (33,33%) and grade II in 4 patients (22,22%). No toxicities grade ≥ 3 were described and none of the patients developed gastrointestinal chronic toxicity. Conclusion Preliminary data shows that this schedule is an optimal option for unresectable esophagus-gastric tumors in elderly patients in order to achieve good local control with palliation of the main presenting symptoms in these tumors, such as dysphagia and bleeding. Longer term follow-up should be analysed to confirm these data. PO-1055 Recursive partitioning model based analysis for oligometastatic colorectal cancer treated with SBRT C. Franzese 1 , T. Comito 1 , D. Franceschini 1 , M. Loi 1 , E. Clerici 1 , P. Navarria 1 , F. De Rose 1 , A. Tozzi 1 , L. Di Brina 1 , P. Mancosu 1 , G. Reggiori 1 , S. Tomatis 1 , M. Scorsetti 1 1 Humanitas Research Hospital, Radiotherapy and Radiosurgery, Rozzano Milan, Italy Purpose or Objective Liver and lung are common sites of metastases from colorectal cancer (CRC). Stereotactic body radiation therapy (SBRT) represents a valid treament, with high rates of local control (LC). In this study we applied recursive partitioning model based analysis (RPA) to define class risks for overall survival (OS) and progression free survival (PFS) in oligometastatic CRC patients.

coverage and normal tissue sparing. 1-years PFS and OS were 20% and 27.3%, respectively. Conclusion Hypofractionated VMAT was feasible, safe, and effective to deliver definitive radiation in locally advanced oesophageal cancer patients, non-suitable for a standard treatment. PO-1053 Involved-field radiation therapy for treatment of locally advanced pancreatic adenocarcinomas. G.S. Munro 1 , R.C. Fogaroli 1 , A.C.A. Pellizzon 1 , D.G. Castro 1 , G.R.M. Gondim 1 , M.L.G. Silva 1 , M.J. Chen 1 , H. Ramos 1 1 A C Camargo Cancer Center, Radiotherapy Department, São Paulo, Brazil Purpose or Objective To analyze if chemotherapy , involved field radiation therapy (IFRT) and surgery for borderline tumors, is appropriate for treatment of borderline and unresectable pancreas adenocarcinomas. Material and Methods Clinical records of 41 consecutive patients treated from March 2012 until March 2018, with borderline or unresectable pancreatic adenocarcinoma were analyzed. All patients were evaluated with physical examination, chest CT, protocol multiphase pancreas CT, tumor markers (CEA and CA 19-9) and laparoscopy for borderline cases. Patients with borderline tumors were treated with neoadjuvant chemotherapy (Folfirinox or Folfox scheme, median: 6 cicles) followed by radiotherapy ( total dose of 50 Gy in 25 fractions) and surgery after four weeks for patients with resectable tumors after CT reassessment. Patients with unresectable tumors were treated with chemotherapy (Folfirinox, Folfox or gemcitabine-based scheme, median: 6 cicles) followed by radiotherapy (total dose of 54 Gy in 27 fractions). For all patients the IFRT was made with GTV encompassed the primary tumor and lymph nodes considered clinically positive by imaging exams and planning target volume (PTV) with margins of 2 cm in the craniocaudal axis and 1 to 1.5 cm in the other axes concomitant with 5FU or capecitabine. Patients were followed with abdominal CT and tumor markers every 3 months in the first and second year and every 6 months from the third year of follow-up and PET-CT when indicated. Local failure (LF) was defined as an increase in radiographic abnormality within the PTV. Elective nodal failure (ENF) was defined by recurrence in any lymph node region outside of the PTV. Any other failure was defined as a distant failure (DF). Results The median age of the patients was 68 years (range: 44 to 80 years), 20 patients (48,7%) were male, and respectively 14 (34%) and 27(66%) patients presented tumors of stage II and III (AJCC, eighth ed.,2017). Most patients (73,1%) had tumors located in the pancreas head. Twelve patients (29%) underwent surgery with RO resection and 29 patients (71%) presented tumors considered unresectable. With a median follow-up of 18 months, the median survival for all patients was 23 months, with higher survival for operated patients (p=0,001) (Figure 1). Tumor recurrences were observed in 32 patients and classified as LF, DF, LF and DF in respectively 6 (18.8%), 20 (62.5%), and 5 (15.6%) patients. Only 1 patient (3.1%) had LF and ENF. No acute or late RTOG grade 3 gastrointestinal side effects related to radiotherapy were reported.