ESTRO-EANO guideline on target delineation and radiotherapy details for glioblastoma

Background and Purpose: Target delineation in glioblastoma is still a matter of extensive research and debate. This guideline aims to update the existing joint European consensus on delineation of the clinical target volume (CTV) in adult glioblastoma patients. Material and Methods: The ESTRO Guidelines Committee identified 14 European experts in close interac-tion with the ESTRO clinical committee and EANO who discussed and analysed the body of evidence con-cerning contemporary glioblastoma target delineation, then took part in a two-step modified Delphi process to address open questions. Results: Several key issues were identified and are discussed including i) pre-treatment steps and immo-bilisation, ii) target delineation and the use of standard and novel imaging techniques, and iii) technical aspects of treatment including planning techniques and fractionation. Based on the EORTC recommenda-tion focusing on the resection cavity and residual enhancing regions on T1-sequences with the addition of a reduced 15 mm margin, special situations are presented with corresponding potential adaptations depending on the specific clinical situation. Conclusions: The EORTC consensus recommends a single clinical target volume definition based on post-operative contrast-enhanced T1 abnormalities, using isotropic margins without the need to cone down. A PTV margin based on the individual mask system and IGRT procedures available is advised; this should usually be no greater than 3 mm when using IGRT. (c) 2023 The Authors. Published by Elsevier B.V. Radiotherapy and Oncology 184 (2023) 109663 This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This guideline aims to update the existing European consensus on delineation of the clinical target volume (CTV) in adult glioblastoma patients. It discusses key issues including pre-treatment steps, target delineation, and technical aspects of treatment. Based on the EORTC recommendation, a single CTV definition using post-operative contrast-enhanced T1 abnormalities is recommended, without the need to cone down. The PTV margin should be based on individual mask system and IGRT procedures, usually no greater than 3 mm.