Glioblastoma invasion of neural stem cell regions; molecular patterns and survival rates.

Glioblastoma is an aggressive form of brain cancer and poses a challenge in treatment due to its profound heterogeneity and capacity for extensive infiltration into the brain parenchyma. Research has shown glioblastomas near the ependyma have poorer survival rates. Therefore, our aim was to identify distinct molecular features of glioblastoma invading the ependyma of lateral ventricles and neural stem cell region and the survival prognosis of these patients. A retrospective review of 170 patients with a new histologically confirmed diagnosis of glioblastoma between 2018 and 2019. Patients were excluded if they were less than 18-years-old, did not have a histological diagnosis, or had missing data. Overall survival (OS) data was analysed. Statistical analysis included Kaplan-Meier survival curves, log rank tests and Cox regression. A total of 170 patients were included (mean age 61 ± 11.3 years; 54% male). Tumours contacted the ependyma in 69 patients and did not in 101. The most common tumour locations were temporal (31%), frontal (29%), and parietal (21%) lobes. Preoperatively, 65% had a performance status of 0-1. Biopsy alone was performed in 19%, subtotal resection (STR) in 48%, and gross total resection (GTR) in 32%; GTR was more common in non-ependyma contacting tumours (40% vs. 20%). MGMT promoter was unmethylated in 64% of patients. Mean overall survival was significantly lower in patients with ependymal contact compared with non-contacting tumours (11.9 vs. 17.4 months, p = 0.004). On multivariable analysis, ependymal contact remained independently associated with poorer survival. No significant association was found between MGMT status and ependymal contact or tumour epicentre distance. Overall, our study reinforces the prognostic relevance of glioblastoma contact with the ependymal and subventricular zones. Tumours involving these regions were associated with poorer overall survival.