ESTRO 38 Abstract book

S696 ESTRO 38

are of great concern especially for mediastinal tumors. It is therefore important to reduce normal tissue dose. Our aim was to evaluate local experience of radiotherapy for mediastinal tumors comparing deep inspiration breath- hold (DIBH) and free breathing (FB) technique with intensity-modulated radiotherapy (IMRT) in regards to Since October 2017 12 patients have been planned with both DIBH and FB technique for mediastinal lymphomas according to ILROG guidelines. Data on histology, chemotherapy, prior cardiac or lung malfunction and radiotherapy was obtained from the patient files. Target delineation was based on current international guidelines and patients were treated with 24-36 Gy; 2 Gy per fraction. Two IMRT plans were calculated and compared for each patient: one for FB and one for DIBH. All plans were simulated in Eclipse (version 13.7.14, Varian Medical Systems) with the AcurosXB 13.7.14 algorithm using 6-MV photon beams. The IMRT plans consisted of 5 to 7 fixed fields. The dosimetric parameters retrieved for the statistical analysis were PTV coverage, mean heart dose, mean lung dose, and lung V5 and heart V20. Results 12 patients were planned with both DIBH and FB IMRT. The patient cohort consisted primarily of men (8 male, 4 female) with a median age of 37 years (range 10-62). All patients received chemotherapy as initial treatment according to national guidelines. Seven patients were treated with radiotherapy in FB and five patients were treated in DIBH. There was no difference in age, total dose, CTV volume or CTV relation to the heart between patients treated with DIBH and patients treated in FB. Patients treated with DIBH had significantly reduced mean dose to total lung, V5 total lung , mean heart dose and V20 heart when comparing DIBH IMRT and FB plan IMRT (p<0.5). For three patients, plan robustness and DIBH instability contributed to treatment choice. Conclusion The experience with DIBH IMRT is still limited in our department. Surprisingly, in the first 12 patients, DIBH IMRT was the treatment of choice in only five patients based on reduced doses to lungs and heart. The remaining seven patients were treated with FB IMRT, since no gain in normal tissue doses was obtained with DIBH IMRT. Further data is needed to properly select patients for DIBH IMRT and thereby individualize the radiation plan for the individual patient. EP-1268 Primary radiation therapy in stage I/II indolent orbital lymphoma: a single-center analysis C. Eze 1 , I. Friedrich 1 , D. Reitz 1 , C. Belka 1 , M. Li 1 1 University Hospital LMU Munich, Department of Radiation Oncology, Munich, Germany Purpose or Objective Non-Hodgkin Lymphoma is a heterogenic group of malignant diseases, which originate from the lymphatic system. They can be subdivided into B- and T-Cell- Lymphoma and classified into indolent/low-grade and high-grade/aggressive lymphoma. Radiotherapy is well- established in the management of stage I/II (Ann Arbor classification) indolent lymphoma. We conducted this retrospective analysis to evaluate the outcomes of patients with localized indolent orbital lymphoma who were treated at our center with definitive radiotherapy. Material and Methods We retrospectively reviewed the medical charts of 47 patients (12 males, 35 females) with 52 lesions treated at our center from 1994- 2012 for histologically confirmed indolent orbital lymphomas. Median age at diagnosis was 63.5 years (range: 20-92) with 25 lesions on the right and 27 on the left. Five patients presented with bilateral involvement. The predominant histological subtype was mucosa-associated lymphoid tissue lymphoma in 84.6% of normal tissue doses. Material and Methods

Purpose or Objective For patients who experience relapse or refractory Hodgkin Lymphoma (R/R HL), the standard treatment option is high-dose chemotherapy followed by autologous stem cell rescue or transplant (HDT/ASCR). However about 50% of patients will have recurrence after HDT/ASCR and have worse prognosis. The anti-PD1 checkpoints inhibitors have remarkably improved outcomes of patients with R/R HL after HDT/ASCT. On the other hand, radiotherapy is an entire component of salvage therapy and its efficacy is now well established in term of local disease control in sites of R/R HL. Defining the optimal modality and timing of radiotherapy as these new agents arrive is a challenge. The purpose of our paper is to add at the literature two new cases of combination of radiotherapy with immunotherapy in patients who relapse after HDT/ASCT and consolidation with Brentuximab Vedotin (BV) . Material and Methods Clinical data were retrospectively collected using the computerized medical records available at the Curie Institute and Cochin Hospital. All imaging have been integrated into the local imaging software and re-read at Institut Curie. Results Case 1: a 27 year-old man was diagnosed in 2015 with stage IV classic Hodgkin Lymphoma, with sus and under diaphragmatic lymph nodes and multiple bone lesions. After 4 cycles of BEACOPP, there was a persistence of a cervical lymph node and mediastinum uptake (Deauville score 4). The patient received a second line with BV-DHAX followed by autologous stem cell transplant (ASCT) in April 2016, resulting in complete metabolic response. A consolidation treatment with BV was initiated. The patient relapsed in June 2017 with cervical and mediastinal lymph nodes (confirmed by biopsy). It was decided an involved sites radiotherapy (30 Gy in IMRT) followed with nivolumab. The patient had now 26 cycles of nivolumab and is in complete response since the third injection. Case 2: A 21 year-old woman was diagnosed in 2015 with classic Hodgkin Lymphoma stage IIAa, Bulky +. After 2 cycles of BEACOPP, Deauville score was 3. The treatment was de-escalated with ABVD. After 4 cycles, there was a marked increase of the mediastinum uptake . The multidisciplinary team of Cochin opted for a salvage chemotherapy by Brentuximab-DHAX, followed by ASCT and resulting in complete metabolic response. The patient then received a consolidation treatment with BV. The patient relapsed in may 2015 with supra-dipahragmatic nodes and reappearance of the mediastinal mass confirmed by biopsy. The patient received a localized radiotherapy of the mediastinum followed by Nivolumab. After 30 cycles of nivolumab, complete response was maintained, nivolumab was stopped since October 2017 and the patient is still in complete response. Conclusion Involved sites radiotherapy followed by nivolumab is an interesting option for patients with RR/HL who experience a localized relapse after ASCT. This combination may increase the response to checkpoint inhibitors and allow to stop them. EP-1267 Deep Inspiration Breath-Hold versus free breathing radiotherapy in mediastinal lymphoma A. Iversen 1 , H.R. Mortensen 1 , Hanne Krogh Rose 1 , Jolanta Hansen 1 1 Aarhus University Hospital, Department of Oncology and Medical Physics, Aarhus C, Denmark Purpose or Objective Radiotherapy plays an important role in the treatment of mediastinal lymphomas as part of combined modality treatment. However, late effects, e.g. cardiac and lung toxicity as well as secondary cancers due to radiotherapy,