Clinical correlates of subventricular zone-contacting glioblastomas: a meta-analysis

INTRODUCTION. The clinical and molecular correlates of glioblastomas (GBMs) contacting the subventricular zone (SVZ+ GBM) are unknown. This work aimed to reveal any such correlates that may help explain their increased GBM malignancy. EVIDENCE ACQUISITION. A meta-analysis was, therefore, conducted to assess whether tumor's MGMT promoter methylation status, isocitrate dehydrogenase (IDH) mutation status, volume, and extent of resection as well as patients' age at diagnosis and preoperative Karnofsky performance status score (KPS) correlate with SVZ contact by GBM. In addition, available imaging of GBM patients in The Cancer Imaging Archive was assessed for SVZ contact and their corresponding clinical and molecular variables were obtained through The Cancer Genome Atlas (TCGA) database. EVIDENCE SYNTHESIS. Twenty-one studies were identified through PubMed and EMBASE database search. This review included 257 patients identified from the TCIA/TCGA database. MGMT promoter methylation status (summary odds ratio [OD], 1.18 [0.84-1.66], P=0.34), IDH mutation status (OD: 0.63 [0.20-1.99], P=0.43), and patients' age of diagnosis (summary mean difference, MD, 0.10 years [-1.85, 2.05], P=0.92) did not associated with SVZ contact of the GBM. However, SVZ+ GBMs were significantly larger than SVZ- GBMs (MD: 17.3 cm(3) [8.70-25.8], P<0.0001). SVZ+ GBM patients had lower KPS scores (MD: -3.33 [-5.31-(-1.35)], P=0.001) and were half as likely to receive a gross total resection (OD: 0.50 [0.40-0.64], P<0.00001). CONCLUSIONS. Additional, large studies that rigorously control for all the known clinical and molecular prognosticators, especially extent of resection and preoperative KPS scores, are needed to evaluate whether SVZ contact by GBM independently influences survival.