Slevin F, Aitken K, Alongi F, Arcangeli S, Chadwick E, Chang AR, Cheung P, Crane C, Guckenberger M, Jereczek-Fossa BA, Kamran SC, Kinj R, Loi M, Mahadevan A, Massaccesi M, Mendez LC, Muirhead R, Pasquier D, Pontoriero A, Spratt DE, Tsang YM, Zelefsky MJ, Lilley J, Dickinson P, Hawkins MA, Henry AM, and Murray LJ
Introduction: Stereotactic Ablative Radiotherapy (SABR) is increasingly used to treat metastatic oligorecurrence 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 regarding 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 statements 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, pre-treatment 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., Competing Interests: Declarations/conflicts of interest statement FS is a Clinical Research Fellow supported by a Cancer Research UK Centres Network Accelerator Award to the ART-NET consortium (grant number A21993). FA reports speaker honoraria and consultancy for Varian and Elekta. BAJF reports institutional research funding grants from Italian Association for Cancer Research (AIRC), FIEO-CCM & FUV and Accuray, outside of the submitted work. BAJF reports travel expenses/speaker fees from Janssen, Ferring, Bayer, Roche, Astellas, Elekta, Carl Zeiss, Ipsen, Accuray and IBA, outside of the submitted work. MAH is supported by funding from the NIHR Biomedical Research Centre at University College London Hospitals NHS Foundation Trust. AMH is supported by grants from Cancer Research UK (award number 108036), National Institute for Health Research (NIHR) (award number 111218), Medical Research Council (MRC) (award number 107154) and Sir John Fisher Foundation (charity, no award number). LJM is an associate professor supported by a Yorkshire Cancer Research funded by Yorkshire Cancer Research (award number L389LM)., (Copyright © 2021 Elsevier B.V. All rights reserved.)