P18.22.B GLIOBLASTOMA IN 2021, DEVELOPING A LARGE INDIVIDUAL PATIENT DATABASE TO INVESTIGATE OUTCOMES AND TREATMENT PATTERNS
Authors: Robinson S D , Clark M , Rathbone M , Black L , Kovacs B , Augustine P , Hatton R , Lathangue H , Wontumi S , Conkey D , Rayner L , Theodoulou M , Kalra B , Fullagar A , Lachmann E , Durage P T T , Counsell L , Pillai V , Christodoulou P , Teoh M , Bowman M , Williams A , Norris T , Iqbal N S , Abdelsadig M , Kingdon S , Yogalingham K , Duffy D , Lau S E , Kahan J , Olukiran G , Heckelmann M , Giamas G , Chandy E , Critchley G 
Published: October 2024

Abstract

BACKGROUND
Glioblastoma (GBM) is a relatively rare but aggressive tumour with poor outcomes. Most real-world data sets rely on extended time periods to include sufficient patients for analysis. However, diagnostic classifications and treatment patterns change over time adding uncertainty regarding current patient outcomes.

MATERIAL AND METHODS
We performed an international multicentre retrospective study to identify pathologically confirmed GBMs diagnosed in 2021. We describe real-world outcomes and treatment patterns in this up-to-date cohort diagnosed according to WHO CNS 5 criteria.

RESULTS
944 pathologically confirmed GBMs have been identified from 31 centres (range 6-70/centre). Median age was 63 (range 18-85), 65% were male and 76% were performance status 0-1. Headache and motor deficits were the most frequent presenting feature (33% each), followed by speech deficits and seizures (27% each). 77% required dexamethasone and 47% anti-epileptic drugs at diagnosis. Tumours were primarily temporal (45%) followed by frontal (35%). 23% had multifocal tumours. Median time from MRI to surgery was 15 days (range 0-869). MGMT was unmethylated in 44% and methylated (&gt;10%) in 23%. Biopsy was performed in 31%, and 34% had &gt;95% resection. Radiotherapy (RT) was used in 80% with a median planning target volume of 334cm3. An additional pre-RT MRI was performed in 43%, demonstrating rapid early progression in 27% which was negatively associated with median overall survival (mOS) (10.8 vs 15.7 months, p&lt;0.001). 1 patient used tumour treating fields. 747 patients had ≥1 surveillance MRI (79%). The 1st MRI demonstrated progression in 41% and indeterminate findings in 22%. In total, 27% of patients with surveillance imaging demonstrated indeterminate findings. This was mostly investigated with repeat structural MRI (77%), whilst 8% had spectroscopy and 23% perfusion imaging, and 57% confirmed progression. Only 9% developed pseudoprogression (PsP) which was associated with improved mOS (vs no-PsP, p=0.003). Median progression free survival was 7.4 months. Progression occurred in 75%, of whom 49% had 2nd line treatment, primarily systemic therapy (73%) followed by repeat surgery (19%). For all patients, mOS was 11.0 months. 48% had conventional chemoRT (mOS 16.7 months), 12% hypofractionated chemoRT (mOS 10.9 months), 11% hypofractionated RT (mOS 8.4 months), 3% had temozolomide (TMZ) (mOS 6.9 months) and 17% had no oncological treatment (mOS 2.5 months). After identifying factors on univariate analysis, female gender, greater MGMT methylation, greater surgery extent, increased RT intensity (none &lt; palliative &lt; hypofractionated &lt; conventional) and adjuvant TMZ were significantly associated with better OS on multivariate analysis.

CONCLUSION
We present a large individual patient database of well characterised glioblastoma patients diagnosed in a single year according to WHO CNS 5.