ESTRO 2021 Abstract Book

S1228

ESTRO 2021

In contrast, Global Mental Health demonstrated statistically significantly higher impact in mental health for Colorectal-Anus(1.77; 95% CI: 0.5–3.0), Esophagus-Gastric(1.93; 95% CI: 1.1–2.7), and H&N(2.95; 95% CI: 2.5– 3.4) patients; however, none reached MCID. Mean scores for ranged from a 0.31-point improvement to 2.95- point decline. Conclusion This large, multi-site prospective registry demonstrates that the PROMIS-10 Global Physical Health is sensitive in identifying clinically meaningful changes due to RT in patients with typically higher burden, chemo-RT treated tumors for Colorectal-Anus, Esophagus-Gastric, and H&N cancers. However, it did not detect meaningful changes for other cancer patients receiving RT, including patients with GU and breast cancer, demonstrating the need for investigation into other QOL measures while ensuring a balance between clinical utility and patient survey burden. PO-1499 1.5T MR-guided daily adaptive radiotherapy: preliminary clinical report of the first 2000 fractions. M. Rigo 1 , F. Cuccia 1 , V. Figlia 1 , N. Giaj-Levra 1 , R. Mazzola 1 , L. Nicosia 1 , F. Ricchetti 1 , D. Gurrera 1 , A. De Simone 1 , S. Naccarato 1 , G. Sicignano 1 , R. Ruggieri 1 , F. Alongi 1 1 IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, Negrar di Valpolicella, Italy Purpose or Objective 1.5T MR-linac improves target volume and adjacent organs-at-risk (OARs) visualization, ensuring high precision in radiation treatment delivery. Moreover, daily MR-imaging allows on-table adapted planning and real-time intra-fraction imaging without additional exposure to radiation. MR-guided treatments represent an extraordinary resource and a step-forward in the field of precision radiation medicine. Herein we present the preliminary report of the first 2000 fractions delivered at our department. We aim to describe the clinical workflow, feasibility and patient-reported tolerability (PROMs) by means questionnaires prospectively assigned at baseline and after daily-adapted RT. Materials and Methods Since 15 th October 2019, Elekta Unity MR-linac is clinically available in our department. The hybrid system consists of 1.5T MR scanner with 160-leaf collimator equipped 7MV FFF beam linear accelerator. Two different workflow were used depending on the OARs daily anatomical situation: Adapt To Position (ATP) workflow where the reference plan position is adjusted rigidly to match the position of the targets and OARs, and Adapt To Shape (ATS) workflow where a new plan is created to better match the anatomy of the day. Both workflows include an initial 3D MRI scan for plan adaptation, another one for verification after planning and before beam on, a real-time intra-fraction MR imaging on sagittal and coronal axis, and a last 3D MRI scan to check intra- fraction movements and OARs deformations. Toxicity and quality of life were assessed at baseline and after treatment using the Common Terminology Criteria for Adverse Events v5.0, International Prostatic Symptoms Score (IPSS), ICIQ-SF, IIEF-5, and EORTC-QLQ-C30 and PR-25 questionnaires. Results Between October 2019 and February 2021, 263 patients with 308 target sites were treated with MR-guided radiation therapy in 2000 total fractions. Median patient age was 70 years (range 39 – 86). Among 308 tumor sites, the most frequently treated region was pelvis (n= 225, 73%). The most common diagnosis was prostate cancer (n= 207). On–table adaptive radiation therapy was used at every treatment session: ATP workflow in 57 fractions (3%) and ATS workflow in 1943 fractions (97%), respectively. Median prescribed dose was 35 Gy (range 20–67.5 Gy) in median 5 fractions (range 5–30). Mean total treatment time was 43 minutes (range 20– 56). Treatments were well-tolerated and no acute grade>2 toxicities were reported. Concerning the PROMS, all questionnaires showed no relevant deterioration between the pre- and post-RT evaluation, except for the fatigue item in EORTC-QLQ C30 questionnaire that declined after RT. Conclusion MR-guided radiation treatment using 1.5T MR-linac has been successfully implemented into clinical routine clinical at our department. The data reported support an optimal profile of tolerability and feasibility of daily on-table adaptive radiation therapy in acceptable time slots. These results are confirmed by PROMs. PO-1500 Stereotactic Body Radiation Therapy for oligorecurrent thymoma: a monocentric experience M. Sepulcri 1 , C. Paronetto 1 , V. Santoro 1 , A. Gorza 1 , F. Gessoni 1 , A. Scaggion 2 , M. Fusella 2 , M. Muraro 1 1 Veneto Institute of Oncology IOV-IRCCS, Radiation Oncology, Padua, Italy; 2 Veneto Institute of Oncology IOV- IRCCS, Medical Physics, Padua, Italy Purpose or Objective Thymic malignancies are rare entities. D ue to the lack of published data, there is no strong evidence available for the best management of recurrent thymoma. Despite radical surgery, the recurrence rates range between 10% and 30%. The most common thymoma’s metastatic sites are the pleura and the lungs; the treatment of the oligometastatic disease is usually surgical when feasible, while chemotherapy is preferred in case of a polimetastatic disease. In this setting radiotherapy has been historically reserved for symptoms palliation, but the development of SBRT allows a further line of treatment for oligometastatic patients who either refuse surgery or are not eligible for it. The purpose of this study was to examine the disease local control (LC) and acute toxicities following SBRT. Materials and Methods From November 2018 to December 2020, 9 patients for a total of 16 thymoma metastases have been treated in our centre using a FFF-RapidArc with 6MV and daily kV-CBCT. All of the patients underwent surgery for the primary tumor with or without neoadjuvant chemotherapy, followed by adjuvant RT except in one case. The best approach for all the recurrences was discussed at a multidisciplinary board. The patients characteristics are listed in the table below.