SC-20 * SUBVENTRICULAR ZONE INVOLVEMENT IN GLIOBLASTOMAS - DOES IT PREDICT AN ADVERSE OUTCOME?

Abstract

INTRODUCTION: Recently it has been shown that glioblastomas (GBM) arising in close proximity to known stem cell regions in the human brain have an aggressive behaviour and may confer an adverse outcome. Its implications on survival however remain unclear. METHODS: 104 consecutive GBMs were analysed in this study. Radiology was reviewed and tumor relationship to subventricular zone (SVZ) recorded. Routine clinical, surgical, and treatment details were recorded. Progression free and overall survivals were calculated. Univariate and multivariate analysis was performed to assses the role of known prognostic markers (age, KPS, RPA class, extent of resection ) as well as relation of the tumor to the SVZ. Various immunohistochemical markers were tested as surrogate markers for proliferation, invasive potential, angiogenesis, stemness, and lineage. RESULTS: Radiological (MRI) evaluation revealed involvement of SVZ in 64 (61.5%). Multifocality at presentation was present in 26 cases (25%) of which 20 belonged to the SVZ group (p = 0.06) . Gross total excision was achieved in 90% of those with no SVZ involvement versus 59% of those with SVZ involvement (p = 0.02). Median PFS and OS were 6.9 and 9.9 months respectively. On univariate analysis only RPA class, completion of radiotherapy and chemotherapy were significant for OS and PFS, the latter two being significant on multivariate analysis too. Though not statistically significant, tumors with SVZ involvement had poorer PFS and OS. CONCLUSION: Though SVZ involvement was not statistically significant, it showed a strong trend towards poor prognosis. It may preclude radical resection which can adversely impact the outcome. SVZ involvement can be a potential non-invasive prognostic marker.