ESTRO 2023 - Abstract Book

S760

Monday 15 May 2023

ESTRO 2023

Proffered Papers: Reirradiation

OC-0915 Thoracic re-irradiation: an international patterns of care survey endorsed by ESTRO and EORTC J. Willmann 1 , A.L. Appelt 2 , P. Balermpas 3 , B.G. Baumert 4 , D. de Ruysscher 5 , M. Hoyer 6 , C. Hurkmans 7 , O. Kaidar-Person 8 , I. Meattini 9 , M. Niyazi 10 , P. Poortmans 11 , N. Reynaert 12 , Y. van der Linden 13 , C. Nieder 14 , N. Andratschke 3 1 Paul Scherrer Institute, Center for Proton Therapy, Villigen, Switzerland; 2 University of Leeds, Leeds Institute of Medical Research at St James’s, Leeds, United Kingdom; 3 University Hospital Zurich, Department of Radiation Oncology, Zurich, Switzerland; 4 Cantonal Hospital Graubünden, Institute of Radiation-Oncology, Chur, Switzerland; 5 Maastricht University Medical Center, Department of Radiation Oncology (Maastro Clinic), Maastricht, The Netherlands; 6 Aarhus University Hospital, Danish Centre for Particle Therapy, Aarhus, Denmark; 7 Catharina Hospital Eindhoven, Department of Radiation Oncology, Eindhoven, The Netherlands; 8 Sheba Medical Center, Breast Cancer Radiation Therapy Unit, Ramat Gan, Israel; 9 Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit, Oncology Department, Florence, Italy; 10 University Hospital, LMU Munich, Department of Radiation Oncology, Munich, Germany; 11 Iridium Netwerk, Department of Radiation Oncology, Wilrijk-Antwerp, Belgium; 12 Institut Jules Bordet, Department of Medical Physics, Brussels, Belgium; 13 Leiden University Medical Centre, Department of Radiotherapy, Leiden, The Netherlands; 14 Nordland Hospital Trust, Department of Oncology and Palliative Medicine, Bodø, Norway Purpose or Objective The use of re-irradiation is increasing, propelled by the introduction of new radiation therapy (RT) techniques. However, high-level evidence to guide clinical practice is scarce. Thus, we investigated international patterns of care of re-irradiation (reRT), presenting hereby the thoracic indications. Materials and Methods We conducted an online survey from March to September 2022. The survey was endorsed by the European Organisation for Radiotherapy and Oncology (ESTRO) and the European Organisation for Research and Treatment of Cancer (EORTC) and distributed to radiation/clinical oncologists, as well as on social media (e.g., Twitter). The survey was split into five sections according to anatomical regions. Participants answered the sections matching their clinical focus. Each section included 14 multiple-choice questions, covering distinct parts of the reRT workflow, including indications, planning & delivery techniques, and follow-up. Percentages in the following refer to the total number of participants answering each question. Results In total, 371 physicians responded to the survey, of which 221 concerning thoracic reRT. The most common cancer types treated with re-irradiation were locally recurrent lung cancer (86%), lymph node metastases (79.2%) or lung/pleural metastases (71%) (Fig 1A). Persistent grade 3 or higher toxicity (76.8%) from previous RT and an ECOG performance status of >2 (65.5%) were the most common conditions precluding thoracic reRT (Fig. 1B). For 52% of the respondents, the minimum interval after which they would consider re-irradiation was 6-12 months (Fig. 2A). In the postoperative setting, 33.6% of the respondents would not deliver reRT, whereas 35.5% would after R1-resection and 35.7% only in case of gross residual disease. ReRT was intended to achieve local control (89.6%) or to alleviate symptoms (69.2%). For treatment planning, most participants co-register CT (89.5%) and/or PET (87.2%) with the planning CT from initial RT (69.9%), using rigid image registration (70.6%). Assuming (partial) recovery of organs at risk (OAR) from RT may allow for higher cumulative doses to be accepted. For the chest wall, 54.4% of the participants allowed higher cumulative doses, while 48.2% and 47.7% did so for lungs and spinal cord, respectively (Fig. 2B). VMAT (87.3%) and/or SBRT (79.6%) are most commonly utilized to deliver re-irradiation. CBCT is used by 92.2% of respondents for position verification.

After reRT, 61.1% state that patients are followed-up primarily by a radiation oncologist.