RARE-21. CLINICAL CHARACTERISTICS OF GLIOSARCOMA AND OUTCOME FROM STANDARDIZED TREATMENT RELATIVE TO CONVENTIONAL GLIOBLASTOMA

Abstract

Abstract INTRODUCTION Gliosarcoma (GS) is a rare histopathologic variant of glioblastoma (GBM) characterized by a biphasic growth pattern consisting of both glial and sarcomatous components. Reports regarding its relative prognosis compared to conventional GBM are conflicting and although GS is treated as conventional GBM, supporting evidence is lacking. The aim of this study was to characterize demographic trends, clinical outcomes and prognostic variables of GS patients receiving standardized therapy and compare these to conventional GBM. METHODS 680 GBM patients, treated with maximal safe resection followed by Stupp’s regimen (radiotherapy with concomitant and adjuvant temozolomide) at a single institution, were retrospective reevaluated by reviewing histopathological records and tumor tissue for identification of GS patients. Clinicohistopathological characteristics obtained via assessment of medical records and imaging analysis were compared between the GS and GBM cohorts. Kaplan-Meier survival estimates were compared with log-rank testing, while cox-regression modeling tested for prognostic factors in GS patients. RESULTS The cohort revealed 26 primary gliosarcoma (PGS) patients (3.8 %) and 7 secondary gliosarcoma (SGS) patients (1.0 %). Compared to conventional GBM tumors, PGS tumors were significantly more often located in the temporal lobe (53.8 %, p = 0.006) and MGMT-unmethylated (73.9 %, p = 0.009). No significant differences were found between PGS and conventional GBM in progression-free-survival (6.8 and 7.6 months respectively, p = 0.105) and in overall survival (13.4 and 15.7 months respectively, p = 0.201). Also, survival from recurrence was not significant different between PGS, SGS and GBM (5.8, 8.6 and 7.4 months respectively, p = 0.694). MGMT status was the only factor prognostic for PGS survival (p = 0.022). CONCLUSION Despite tumor difference between GS and GBM, the patients present similar survival outcome from standardized treatment. This support continues practice of radiation and temozolomide for GS patients.