gms | German Medical Science

Objective: Glioblastoma (GBM) is the most common type of primary brain tumor with a dismal prognosis. Several parameters are known to influence survival, comprising extend of resection, Karnofsky performance score (KPS), MGMT promotor methylation and are used in routine diagnostic. Other parameters like multilocularity and proliferation indices are not routinely used. The aim of the present study was to analyze the influence of different routinely and not routinely used markers on survival of patients suffering from GBM.

Methods: All adult cases (≥18 years) with primary GBM operated at our institution between 2004 and 2014 were included in this survey. The association of gender, age, operation modality, KPS, MGMT promotor methylation, IDH1/2 mutational status, multilocularity, and Ki67 proliferation index on two years survival was analyzed in univariate and multivariate cox regression models. Statistical analyses were conducted using SPSS version 22.0.

Results: 577 patients were analyzed with a mean age of 62.3 (18-84) years. Median OS with standard deviation was 13.5 months (±15). MGMT promoter methylation was associated with a higher mean OS (15.6 months). IDH1/2 mutational status could be determined in 250 cases whereof 10 (4%) were mutated and associated with significant better OS compared to the wildtype (39 versus 10 months). In 249 (43.15%) cases the tumor was localized in a single lobe; single lobe localisation was associated with a significant better two years survival (p<0.01). Mean Ki67 proliferation index increased from 3% with single lobe infiltration to 11.8% with multiple lobe infiltration, up to 16.7% with infiltration of the contralateral side. Multivariat analysis for two years survival revealed IDH1 wildtype (Hazard ratio (HR): 4), age over 70 years (HR 2.4), unmethylated MGMT promotor (HR:1.8), postoperative KPI under 70 (HR 1.6), and multilocularity (HR 1.4) as significant, independent parameters for worse survival.

Conclusion: The results of the present study confirm well-known parameters like MGMT promoter methylation, KPS, and age as independent prognostic factors for survival, and reveal IDH1 mutational status, as well as multilocularity as further independent prognostic markers for survival. The dismal prognosis of multilocular involvement is significantly associated to increasing Ki67 proliferation index.