3468 - International Delphi Consensus on Endpoints Selection, Reporting, and Clinical Response Criteria for SBRT in Bone Metastases
Presenter(s)
S. F. Lee1,2, H. C. Y. Wong3, E. S. A. Oldenburger4, R. Srinivas5, G. N. Marta6, A. W. Chan7, D. Rades8, Y. M. van der Linden9, J. M. van der Velden10, Q. N. Nguyen11, I. J. Choi12, C. Hircock13, C. Doccioli14, C. Cosma15, S. Caini16, A. Rembielak17, V. Vassiliou18, P. Bonomo19, P. A. S. Johnstone20, S. R. Alcorn21, C. Johnstone22, C. B. Simone II23, P. Hoskin17,24, E. Chow13, and S. Ryu25; 1National University Cancer Institute, National University Hospital, Singapore, Singapore, 2Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore, 3Department of Oncology, Princess Margaret Hospital, Kwai Chung, Hong Kong, 4University Hospitals Leuven, Leuven, Belgium, 5University of British Columbia, Vancouver, BC, Canada, 6Department of Radiation Oncology, Hospital Sírio-Libanês, Sao Paulo, Brazil, 7Department of Radiation Oncology, BC Cancer - Vancouver, Vancouver, BC, Canada, 8Department of Radiation Oncology, University Medical Center Schleswig-Holstein, Lubeck, Germany, 9Leiden University Medical Centre, Leiden, Netherlands, 10University Medical Center Utrecht, Utrecht, Netherlands, 11The University of Texas MD Anderson Cancer Center, Houston, TX, 12Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY, 13Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 14Institute for Cancer Research, Prevention and Clinical Network (ISPRO), Florence, Italy, 15Medical School of Specialization in Hygiene and Preventive Medicine, University of Florence, Florence, Italy, 16Institute for Cancer Research, Prevention, and Clinical Network (ISPRO), Florence, Italy, 17Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom, 18Bank of Cyprus Oncology Centre, Nicosia, Cyprus, 19Radiation Oncology Unit, Azienda Ospedaliero-Universitaria Careggi, University of Florence, Florence, Italy, 20H. Lee Moffitt Cancer Center and Research Institute, Department of Radiation Oncology, Tampa, FL, 21University of Minnesota Medical Center, Minneapolis, MN, 22Medical College of Wisconsin, Milwaukee, WI, 23New York Proton Center, New York, NY, 24Department of Clinical Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom, 25Department of Radiation Oncology, Stony Brook University Hospital, Stony Brook, NY
Purpose/Objective(s): Significant variability exists in the selection and reporting of endpoints in SBRT trials for bone metastases, limiting comparability across studies. We conducted an international Delphi consensus to establish a core set of endpoints and standardized clinical response criteria.
Materials/Methods: A multi-round international Delphi process was conducted with radiation and clinical oncologists, and musculoskeletal radiologists. The Round 1 survey, developed from a systematic literature review and expert discussions, used a 5-point Likert scale to rate the importance of endpoints, with consensus defined as =75% agreement. Free-text feedback informed item revisions and the addition of new items. In Round 2, participants prioritized endpoints as "required," "recommended," or "optional" across key categories: eligibility criteria, pain and analgesic assessments, response criteria, timing of assessments, endpoints at follow-up, quality-of-life measures, reirradiation considerations, and clinical trial scenarios.
Results: Of 114 invited experts, 83 (73%) completed Round 1 and 74 (89% of Round 1 participants) completed Round 2. In Round 1, 40 of 59 statements (68%) reached consensus and were included in Round 2 prioritization. Of these, 36 (90%) were rated “required,” 2 (5%) “recommended,” and 1 (3%) received a tied result. The remaining 19 statements (32%) were revised based on feedback, with 13 reintroduced in Round 2; 6 (46%) achieved consensus and were retained. Additionally, 23 new items were proposed, of which 9 (39%) reached =75% agreement . Refinements were also made to clarify definitions and establish a minimal core set of endpoints for SBRT trials across different scenarios, including oligometastatic, oligoprogressive, and asymptomatic bone metastases. A newly developed clinical response criteria will also be evaluated and validated.
Conclusion: This international Delphi consensus establishes a standardized framework for selecting, defining, and reporting clinical endpoints and response criteria in SBRT trials for bone metastases. The structured prioritization process has refined key endpoints, with final validation underway. The results will enhance standardized reporting, optimize trial design, and strengthen evidence-based practice.