An international Delphi consensus for pelvic stereotactic ablative radiotherapy re-irradiation

Introduction: Stereotactic Ablative Radiotherapy (SABR) is increasingly used to treat metastatic oligore-currence and locoregional recurrences but limited evidence/guidance exists in the setting of pelvic re-irradiation. An international Delphi study was performed to develop statements to guide practice regard-ing patient selection, pre-treatment investigations, treatment planning, delivery and cumulative organs at risk (OARs) constraints. Materials and methods: Forty-one radiation oncologists were invited to participate in three online surveys. In Round 1, information and opinion was sought regarding participants' practice. Guidance statements were developed using this information and in Round 2 participants were asked to indicate their level of agreement with each statement. Consensus was defined as >75% agreement. In Round 3, any state -ments without consensus were re-presented unmodified, alongside a summary of comments from Round 2. Results: Twenty-three radiation oncologists participated in Round 1 and, of these, 21 (91%) and 22 (96%) completed Rounds 2 and 3 respectively. Twenty-nine of 44 statements (66%) achieved consensus in Round 2. The remaining 15 statements (34%) did not achieve further consensus in Round 3. Consensus was achieved for 10 of 17 statements (59%) regarding patient selection/pre-treatment investigations; 12 of 13 statements (92%) concerning treatment planning and delivery; and 7 of 14 statements (50%) relating to OARs. Lack of agreement remained regarding the minimum time interval between irradiation courses, the number/size of pelvic lesions that can be treated and the most appropriate cumulative OAR constraints. Conclusions: This study has established consensus, where possible, in areas of patient selection, pretreatment investigations, treatment planning and delivery for pelvic SABR re-irradiation for metastatic oligorecurrence and locoregional recurrences. Further research into this technique is required, especially regarding aspects of practice where consensus was not achieved. (c) 2021 Elsevier B.V. All rights reserved. Radiotherapy and Oncology 164 (2021) 104-114

Automated summary

This study utilized the Delphi method to develop guidance statements for pelvic SABR re-irradiation. Consensus was achieved in areas such as patient selection, treatment planning, and OAR constraints, but there were still some disputes regarding certain aspects.