OS12.6.A MOLECULAR GLIOBLASTOMAS - BETTER PROGNOSIS AFTER CORRECTING FOR TREATMENT DIFFERENCES

• Published in: Neuro-oncology (Charlottesville, Va.) Va.), 2024-10, Vol.26 (Supplement_5), p.v29-v30
• Main Authors: Robinson, S D, Clark, M, MacColl, J, Forner, S, Wong, A, Srimat Tirumala, L N K, Hatton, N L, Lathangue, H, Wontumi, S, Conkey, D, Rayner, L, Patel, K, de Boisanger, J, Fullagar, A, Lachmann, E, Durage, P T T, Edlmann, E, Pillai, V, de Luna, P J, Teoh, M, Choudhury, M, Williams, A, Norris, T, Golten, J, Murphy, S, Kingdon, S, Yogalingham, K, Stewart, G, Lau, S E, Kahan, J, Olukiran, G, Heckelmann, M, Giamas, G, Critchley, G, Chandy, E
• Format: Article
• Language: English
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/noae144.087

Abstract BACKGROUND Molecular glioblastoma (mGBM), without classical histological features, was defined in the 2021 WHO classification based on select criteria (EGFR amplification, TERT promoter mutation (pTERT), chromosome 7+/10-). Subsequent validation relied on retrospective patient re-diagnosis and/or historical histological GBMs (hGBMs) controls. Whether pTERT only mGBMs also have a poor prognosis remains uncertain. We comprehensively characterised mGBMs compared to concurrently diagnosed hGBMs. MATERIAL AND METHODS We identified pathologically confirmed GBMs diagnosed in 2021 in a multicentre retrospective study. Patients were diagnosed and treated as per their centre’s standard practice. Most centres offered routine molecular testing. Demographic, tumour and treatment characteristic differences were assessed by unpaired t-test. Kaplan-Meier analysis was from surgery date and survival differences compared by log rank. RESULTS We identified 944 pathologically confirmed GBMs from 31 centres, and 61 were mGBM (9.3% of tested cases). For mGBM patients, median age was 62 (vs 63), 66% were male (vs 64%) and 84% were WHO performance status 0-1 (vs 76%). Seizures were the most common presentation (33 vs 26%, p=0.300), plus significantly more sensory deficits (21 vs 10%, p=0.043) but significantly less speech (13 vs 28%, p=0.002) and cognitive deficits (15 vs 26%, p=0.027). mGBM patients were more likely to have multifocal disease (36% vs 23%, p=0.011) and less likely to have contrast enhancement (69% vs 96%, p10%) methylated (p=0.840). There was a trend for delay from initial imaging to surgery (median 19 vs 15 days) and surgery to radiotherapy (RT) (median 46 vs 40 days), resulting in a significant delay from initial imaging to RT (median 77 vs 57 days, p95% resected 15 vs 35%, p