3500 - International Consensus on Palliative Radiotherapy Endpoints for Bone Metastases Trials: Second Update
Presenter(s)
E. S. A. Oldenburger1, J. Jomy2, J. M. van der Velden3, S. F. Lee4, H. Y. Wong5, M. Spalek6, G. N. Marta7, C. B. Simone II8, A. Rembielak9, P. Hoskin10, Y. van der Linden11, I. Navarro Domènech12, D. Rades13, E. Chow14, P. Wong15, and S. Raman16; 1University Hospitals Leuven, Leuven, Belgium, 2Princess Margaret Cancer Centre, Toronto, ON, Canada, 3University Medical Center Utrecht, Utrecht, Netherlands, 4National University Cancer Institute, Singapore, Singapore, 5Princess Margaret Hospital, Hong Kong, China, 6Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland, 7Department of Radiation Oncology, Hospital Sírio-Libanês, Sao Paulo, Brazil, 8New York Proton Center, New York, NY, 9Division of Cancer Sciences, University of Manchester, Manchester, United Kingdom, 10Mount Vernon Cancer Centre, Middlesex, United Kingdom, 11Leiden University Medical Centre, Leiden, Netherlands, 12Hospital Universitario La Paz, Madrid, Spain, 13Department of Radiation Oncology, University of Lübeck, Lübeck, Germany, 14Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada, 15Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada, 16British Columbia Cancer Agency, Vancouver, BC, Canada
Purpose/Objective(s):
External beam radiotherapy (EBRT) is a key palliative treatment for bone metastases. With advances in clinical practice, standardized endpoints ensure accurate reporting and trial comparability. We have updated the consensus guidelines for EBRT trial endpoints by the International Bone Metastases Consensus Group.Materials/Methods:
The Delphi Method was applied in a two-phase online survey. Experts, including prior consensus contributors and specialists in bone irradiation, participated. Statements required a consensus of =75% agreement. Statements not reaching consensus in Phase I were revised and reassessed in Phase II.Results:
58 experts participated in Phase I and 44 in Phase II; reaching consensus for 37 of 48 (77%) statements, with 16 new/modified items. Key consensus areas included eligibility criteria, pain and analgesic assessments, radiation techniques and dose specifications, follow-up protocols, assessment timing, and cost-effectiveness (Table 1). Quality of life measures were recommended for all trials, and net pain relief and skeletal-related events were introduced as critical endpoints. Debates remained on the optimal pre-treatment assessment timeframe (= 1 week vs. = 48h), timing of first post-EBRT pain assessment (3-day vs. 7-day), and whether to report worst and/or mean pain. While pain response evaluations at 1, 2, and 3 months were accepted, alternative intervals were debated. Follow-up de-intensification after 6 months was considered, but optimal duration was contested as some experts advocated for extended monitoring.Conclusion:
This updated consensus refines EBRT trial design frameworks, promoting standardized reporting and research priorities. The inclusion of new endpoints, such as standardized dose thresholds, reflects current clinical practices. Ongoing evaluation will ensure continued relevance. Abstract 3500 - Table 1: Key findings| Consensus Area | Agreement(%) | Findings |
| Eligibility Criteria | 77-89 | Stratification by tumor type; inclusion of all ages; use of ESTRO-ACROP definition for (un)complicated bone metastases; minimum pain score 2/10 at inclusion |
| Pain & Analgesic Assessment | 87-96 | Pain assessed on a 0-10 scale; body diagram use for pain site; net pain relief as endpoint; oral morphine equivalent use; recording of adjuvant analgesics and steroids. |
| Radiation Techniques & Dose | 75-98 | Highly conformal techniques allowed; CTV limited to affected bone or GTV expansion; dose thresholds per ESTRO-ACROP guidelines |
| Follow-up Protocols | 80-98 | Pain flare follow-up at 7-10 days; follow-up = 3 months includes additional clinical data; follow-up de-intensification = 6 months for treatment effect and retreatment evaluation |
| Endpoints | 75-100 | Pain evaluation at 1, 2, and 3 months; quality-of-life assessments recommended; multiplatform questionnaires. |
| New Endpoints | 100 | Quality-of-life as specific endpoint; skeletal-related events as an endpoint |