gms | German Medical Science

Objective: Limited data are available with regard to the impact of baseline midline shift (MLS) on long-term survival and progression in glioblastoma (GBM). Objective of this study was to analyze the influence of mass effect on survival and progression with due regard for the patient demographics, operative techniques, molecular pathology and postoperative treatment.

Methods: 198 patients with GBM were analyzed retrospectively. MLS was measured on preoperative T2-weighted magnetic resonance images (MRI) at the level of the septum pellucidum. Patients were dichotomized in groups with low (< 10 mm) and high (≥ 10 mm) MLS. Both MLS-groups were compared with regard to survival, progression-free survival (PFS) and postoperative course of Karnofsky Performance Status (KPS). Possible correlations were investigated using univariate -, binary logistic regression-, and Kaplan-Meier analyses.

Results

• Two-sided Fisher’s exact test revealed no statistically significant differences of the confounders between low- and high-MLS group.
• Median survival was 18.0 months (95% CI=15.3-20.7) in the low-MLS group (n=173), and 9.0 months (95% CI=4.8-13.2) in the high-MLS group (n=25), respectively (p=0.045).
• 59.1% (13/22) with an initial high-MLS had a KPS of < 70% after 3 months, whereas 20.5% of the the low-MLS group had a KPS of < 70% (p<0.001).
• Binary logistic regression analysis including the MGMT status, extent of resection, baseline KPS, and MIB-I index revealed low-MLS as the only predictor for survival at 12 months (p=0.046, OR=2.70, 95% CI=1.0-7.2).
• Median PFS was 6.0 months in the high-MLS group and 9.0 months in the low MLS-group (log-rank test; p=0.08).

Conclusion: Initial midline shift ≥ 10 mm seems to be an imaging characteristic which independently predicts the survival rate in glioblastoma.