P17.78 * SECONDARY GLIOBLASTOMA - OUTCOME AND PROGNOSTIC FACTORS

Abstract

BACKGROUND: Prognostic factors and outcome of patients with primary glioblastoma (GBM) are well reported. In contrast, there is limited information about patients with secondary GBM (sGBM). The goal of this work was to report on the outcome of patients with sGBM and to identify prognostic factors. METHODS: We retrospectively analyzed our institutional database of brain tumor patients for clinical patient data. All patients had histological proof of WHO II-III glioma and subsequent WHO IV secondary glioblastoma. Using paraffin embedded tissue we screened for mutations of the isocitrate dehydrogenase-1 (IDH-1) using immunohistochemical staining (IHC) with an R132H (clone H09) specific antibody. We performed uni- and multivariate analyses to identify factors potentially affecting survival. RESULTS: We analyzed 45 patients with histologically proven sGBM. Median age was 41 years. 31 patients underwent radiologically complete resection of sGBM, 14 underwent subtotal resection or biopsy only. Initially, 36 patients had astrocytic tumors, the other suffered from oligodendrogliomas or mixed gliomas; at first diagnosis, there were 18 WHO II tumors, and 27 were WHO III. Median time between first glioma diagnosis and occurence of sGBM was 158.9 weeks; median overall survival (OS) following diagnosis of sGBM was 63.6 weeks. IDH-1 mutations were present in 24 patients and absent in 17; in 4 patients, IHC could not be performed. On univariate analysis, time between first diagnosis and progression to sGBM was a statistically significant factor - patients with an interval >2 years had a better OS (67.4 vs. 60.1 weeks, p = 0.027). Also, patients receiving combined adjuvant radio- and chemotherapy did better than those who only had either therapy (87.3 vs. 54.3 weeks). Following multivariate analysis, IDH-1 (R132H) mutation was associated with longer OS (p = 0.012); there was a trend for patients with initial WHO II tumors having a better prognosis (p = 0.057). Using patient specific data, we established two prognostic groups; patients in the good prognosis group appeared to benefit from complete tumor removal (p = 0.06), while resection did not play a role for the other (p = 0.97). CONCLUSION: Although of relatively young age, prognosis of patients with sGBM is dismal. IDH-1 (R132H) mutation and WHO grade of the initial tumor are associated with OS after progression to sGBM. Patients in the good prognosis group appear to benefit from complete tumor removal, while the others do not.