Outcome and prognostic factors in adult cerebellar glioblastoma

Cerebellar glioblastoma multiforme (GBM) occurs rarely in adults, accounting for 0.4-3.4% of all GBM. Current studies have all involved small patient numbers, limiting the clear identification of prognostic factors. Additionally, while few studies have compared cerebellar GBM to their supratentorial counterparts, there is conflicting data regarding their relative prognosis. To better characterize outcome and identify patient and treatment factors which affect survival, the authors analyzed cases of adult cerebellar GBM from the Surveillance, Epidemiology, and End Results database. A total of 247 adult patients with cerebellar GBM were identified, accounting for 0.67% of all adult GBM. Patients with cerebellar GBM were significantly younger than those with supratentorial tumors (56.6 versus 61.8 years, p < 0.0001), but a larger percentage of patients with supratentorial GBM were Caucasian (91.7% versus 85.0%, p < 0.0001). Overall median survival did not differ between those with cerebellar and supratentorial GBM (7 versus 8 months, p = 0.24), with similar rates of long-term (greater than 2 years) survival (13.4% versus 10.6%, p = 0.21). Multivariate analysis revealed age greater than 40 years (hazard ratio [HR]: 2.20; 95% confidence interval [CI]: 1.47-3.28; p = 0.0001) to be associated with worse patient survival, while the use of radiotherapy (HR: 0.33; 95% CI: 0.24-0.47; p < 0.0001) and surgical resection (HR: 0.66; 95% CI: 0.45-0.96; p = 0.028) were seen to be independent favorable prognostic factors. In conclusion, patients with cerebellar GBM have an overall poor prognosis, with radiotherapy and surgical resection significantly improving survival. As with supratentorial GBM, older age is a poor prognostic factor. The lack of differences between supratentorial and cerebellar GBM with respect to overall survival and prognostic factors suggests these tumors to be biologically similar.