The European Association for Neuro-oncology consensus statement on radiation necrosis

INTRODUCTION: Radiation necrosis (RN) complicates neuro-oncological care, mimicking tumor recurrence and lacking high-level evidence for standardized management. METHODS: A European Association for Neuro-Oncology (EANO) expert panel utilized a three-round Delphi process to create a comprehensive expert opinion document based on the available current scientific evidence. A series of statements, derived from the published literature were created by the experts in each field. Consensus was defined as ≥ 80% agreement using a 5-point Likert scale. RESULTS: After three rounds among 20 experts that included adaptation of statements, the Delphi process reached a consensus (≥80% agreement) on 53 statements out of 57. RN occurs in 4% to 30% of patients, typically appearing 6 to 24 months after radiotherapy for primary (glial) or metastatic brain tumors. Experts identified perfusion MRI and amino acid PET as the most suitable imaging modalities for differentiation from tumor recurrence. While histopathology remains the gold standard, identifying viable tumor cells in irradiated gliomas is challenging due to overlapping cytological features with reactive glia. For symptomatic management, corticosteroids may be tried, and bevacizumab is recommended for corticosteroid-refractory cases, with evidence suggesting profound efficacy even at low doses. Surgery is considered effective for rapid symptom relief and definitive diagnosis in accessible lesions. Laser Interstitial Thermal Therapy (LITT) can be considered an additional treatment option for symptomatic RN. CONCLUSIONS: Despite the absence of Level 1 evidence, these Delphi-survey-formulated recommendations provide actionable guidance for clinical practice. There is a need for prospective randomized trials focusing on symptomatic RN.