ESTRO 2020 Abstract Book

S254 ESTRO 2020

OC-0457 Stereotactic body radiation therapy (SBRT) for oligometastatic soft tissue sarcoma (STS) A. Botticella 1 , D. Jornet 1 , E. Tang 1 , O. Henry 1 , G. Auzac 1 , I. Chabert 1 , S. Dumond 2 , O. Mir 2 , L. Haddag-Miliani 3 , F. Mihoubi 3 , A. Le Cesne 2 , M. Faron 4 , A. Cavalcanti 4 , P. Terrier 5 , J. Adam 5 , C. Honoré 4 , A. Levy 1 , C. Le Pechoux 1 1 Gustave Roussy, Radiation Oncology Department, Villejuif, France ; 2 Gustave Roussy, Oncology Department, Villejuif, France ; 3 Gustave Roussy, Radiology Department, Villejuif, France ; 4 Gustave Roussy, Surgical Oncology Department, Villejuif, France ; 5 Gustave Roussy, Pathology Department, Villejuif, France Purpose or Objective SBRT has an emerging role in the treatment of oligometastatic, oligoremnant and oligoprogressive patients in various tumour histologies. In the management of oligometastatic sarcomas, patients have traditionally been treated with surgical resection, radiofrequency ablation, and/or systemic treatment. We aimed to evaluate the tolerability and the efficacy of SBRT in a retrospective cohort of oligometastatic soft We retrospectively reviewed the records of 55 consecutive oligometastatic sarcoma patients who received SBRT on 72 metastatic lesions between March 2014 and November 2018 at our institution. Local control (LC), distant metastases-free survival (DMFS) and overall survival (OS) rates were assessed using the Kaplan-Meier method.Toxicity was graded using the Common Toxicity Criteria (CTCAE) v. 4.03 and recorded before RT, 45 days after the completion of RT and every 3 months thereafter. Results SBRT was performed for lung metastases in 39/72 (54.2%) lesions, for bone metastases in 29/72 (40.3%) lesions and for liver metastases in 4/72 lesions (5.5%). Five patients out of 55 (9.1%) received concomitant chemotherapy for metastatic disease during SBRT. Image-guided SBRT was delivered either with a Cyberknife (7/72=9.7%) or with a linear accelerator (in VMAT or with static coplanar beams; 65/72=90.3%). The median dose delivered was 45 Gy (Range: 15-66 Gy) in a median number of 5 fractions delivered to the PTV (according to a risk- adapted approach). The median doses delivered to lung/bone/liver metastases were 45/30/45 Gy (Range lung: 45-60; range bone: 30-33; range liver: 45-50) in a median number of 5/3/3 fractions, respectively. The median follow-up was 30.1 months (range: 1-73 months). 2-years LC was 89%; 2-years DMFS was 53%; 2-years OS was 77%. The median OS was 33.6 months (range: 3-73 months). Multivariate analysis showed a significant correlation between OS and a disease-free interval < 32.8 months (calculated between the primary tumour diagnosis and the SBRT for the metastatic disease) and a tumour size < 25 mm (p=0.003 and 0.04, respectively). No grade >3 toxicity was observed. Conclusion To the best of our knowledge, this is the largest cohort of SBRT in oligometastatic metastatic STS.This study shows that SBRT is an effective and safe local treatment option that might be used as an alternative to other local treatments in highly selected patients. tissue sarcomas (STS). Material and Methods

Netherlands ; 4 Radboud university medical center, Department of Radiotherapy, Nijmegen, The Netherlands ; 5 Leids University Medical Centre, Department of Radiotherapy, Leiden, The Netherlands ; 6 Zeeuws Radiotherapeutisch instituut, Department of Radiation Oncology, Vlissingen and Roosendaal, The Netherlands ; 7 Erasmus Medical Center, Department of Medical Oncology, Rotterdam, The Netherlands ; 8 Radiotherapeutisch Instituut Friesland, Department of Radiation Oncology, Leeuwarden, The Netherlands ; 9 MAASTRO clinic Maastricht- GROW school for Oncology and Developmental Biology, Department of Radiation Oncology, Maastricht, The Netherlands ; 10 University Medical Center Utrecht, Department of Radiotherapy, Utrecht, The Netherlands ; 11 Amsterdam University Medical Center, Department of Radiation Oncology, Amsterdam, The Netherlands Purpose or Objective Intraluminal brachytherapy is an established treatment for the palliation of dysphagia in patients with incurable esophageal cancer. However, short-course external beam radiotherapy (EBRT) is the most commonly applied treatment. There is no evidence to support superiority for one modality over the other. We compared improvement of dysphagia after EBRT versus brachytherapy in two prospective studies. Material and Methods We performed a multicenter prospective cohort study of patients with metastasized or otherwise incurable esophageal cancer requiring palliation of dysphagia from September 2016 to March 2019. Inclusion criteria and endpoints were similar to those used in the SIREC trial. Patients were treated with EBRT in 5 fractions of 4 Gy. Data was compared to findings from all patients treated with a single brachytherapy dose of 12 Gy in the SIREC trial. Results were compared between the original cohorts, as well as between 1:1 propensity score-matched cohorts. Primary endpoint was improvement in dysphagia at 3 months without re-intervention. Secondary endpoints included toxicity and time to maximum effect. Results A total of 115 patients treated with EBRT and 93 patients who underwent brachytherapy were eligible for analysis. In the original cohorts, dysphagia improved after EBRT in 79% of patients compared to 64% after brachytherapy (p=0.067). Propensity score matching resulted in 71 patients in each cohort who were well-balanced in baseline. Improvement in dysphagia was observed more frequently after EBRT compared to brachytherapy (84% versus 65%, p=0.044). In patients with effect of treatment, time to first improvement and time to maximum effect was shorter after EBRT compared to brachytherapy. In these patients, first improvement in dysphagia was observed after 2 weeks in 67% after EBRT compared to 35% after brachytherapy, and in 87% versus 58% at 4 weeks. The maximum effect was reached after 4 weeks in 55% after EBRT compared to 33% after brachytherapy. Severe toxicity occurred in 3% of patients after EBRT compared to 13% after brachytherapy. Conclusion Short course EBRT appears superior to brachytherapy in the palliation of dysphagia in esophageal cancer patients. Based on these results, we recommend short course EBRT as the primary treatment for relief of dysphagia.