• G Hallaert, H Pinson, C Van den Broecke, D Vanhauwaert, D Van Roost, T Boterberg, and J P Kalala.
• Department of Neurosurgery, Ghent University Hospital, Gent, Belgium.
• Acta Oncol. 2020 Dec 1; 59 (12): 1474-1479.

BackgroundSeveral studies show that subventricular zone (SVZ) contact of glioblastoma at diagnosis is a negative prognosticator of survival. In this report, we study glioblastoma patient survival, molecular biological and MRI-based volumetric findings according to SVZ contact.Patients And MethodsWe conducted a retrospective study of adult patients diagnosed with supratentorial glioblastoma and uniformly treated with temozolomide-based chemoradiotherapy after surgery. The patient cohort was dichotomized according to tumor contact with the SVZ at diagnosis as determined on preoperative MR imaging. Tumor volume was measured using semi-automated segmentation technique. MGMT-gene promoter methylation and IDH mutation status were determined on stored tumor tissue. Kaplan-Meier survival curves were constructed. Cox regression analysis was used to adjust for known confounding factors of glioblastoma patient survival.ResultsA total of 214 patients were included in the study of whom 68% belonged to the SVZpos group. Median tumor volume was significantly larger in the SVZpos group (33,8 mL vs 15,6 mL; p < .001). MGMT-unmethylated glioblastoma was more frequent in the SVZpos group (61.4% vs 44.9%; p = .028). The overall survival and progression-free survival were 12.2 months and 5.9 months for the SVZpos patient group but 16.9 months and 10.3 months for the SVZneg group (log-rank p = .016 and .007 respectively). In multivariate Cox survival analysis, SVZ contact proved a negative prognostic parameter, independent from age, KPS, extent of resection, MGMT-methylation and IDH mutation status.ConclusionsThis study confirms SVZ contact at diagnosis as an independent negative prognostic factor for glioblastoma patient survival. SVZpos glioblastoma had larger tumor size and a larger proportion of unmethylated tumors than SVZneg glioblastoma. Further research is needed to establish whether the observed differences are solely explained by a different molecular profile of SVZpos glioblastoma or by interaction of glioblastoma with the unique SVZ microenvironment.

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