P13.14.A REPEATED TREATMENT-ASSOCIATED CHANGES IN PATIENTS WITH A DIFFUSE GLIOMA

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2024-10, Vol.26 (Supplement_5), p.v75-v75
• Main Authors: Mechroubi, A, Flies, C M, Dankbaar, J W, Verhoeff, J J C, Robe, P A, Snijders, T J
• Format: Article
• Language: English
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noae144.247

Abstract BACKGROUND Radiological and clinical progression after treatment of patients with a diffuse glioma can be caused by progressive disease (PD) or be an effect of treatment-associated changes/pseudoprogression. These changes may occur more than once in the same patient, but data on such repeated changes are scarce. The goal of this study is to investigate the incidence of repeated treatment-associated changes, as well as the associated clinical and radiological characteristics. MATERIAL AND METHODS In this retrospective mono-centre cohort study, patients with a diffuse glioma (WHO grade 2-4) who were treated with (chemo-)radiation and who developed treatment-associated changes afterwards were included. We reviewed the patient files to identify patients with more than 1 episode of treatment-associated changes. An episode of treatment-associated changes was defined either radiologically, as new or increasing contrast-enhancement (CE) on MRI that subsequently stabilised for ≥12 weeks or regressed for ≥1 month, or histologically, as treatment-associated changes without proliferating tumour. We searched for predictors for repeated treatment-associated changes with univariable odds ratios (OR) and compared the survival between patients with a single versus repeated episodes of treatment-associated changes. RESULTS Of 176 patients with treatment-associated changes, 58 patients (33%) developed 174 repeated episodes, of which 21% were confirmed by histopathology. Most patients (54%) had an IDH-wildtype glioblastoma. The first episode started one month after radiotherapy (median; interquartile range IQR, 0-11). The median duration of the radiological episodes was 32 weeks (IQR, 24.5-60). An oligodendroglioma grade 3 tumour type and an IDH-mutation compared to IDH-wildtype glioblastomas were positive predictors for repeated treatment-associated changes (OR, 8.8 and 5.0; both p,