BACKGROUND Cerebellar glioblastoma multiforme (cGBM) is rare, and although there is a general belief that these tumors have a worse prognosis than supratentorial GBM (sGBM), few studies have been published to support this belief.   
 OBJECTIVE To investigate the effect of cerebellar location on survival through a case-control design comparing overall survival time of cGBM and sGBM patients.   
 METHODS The Surveillance, Epidemiology, and End Results (SEER) registry was used to identify 132 patients with cGBM (1973-2008). Each cGBM patient was matched with an sGBM patient from among 20,848 sGBM patients on the basis of age, extent of resection, decade of diagnosis, and radiation therapy using propensity score matching.   
 RESULTS Within the cGBM, 37% were older than 65 years of age, 62% were men, and 87% were white. Most patients underwent surgery and radiation (74%), whereas only 26% underwent surgical resection only. The median survival time for the cGBM and sGBM matched cohort was 8 months; however, the survival distributions differed (log-rank P = .04). Survival time for cGBM vs sGBM at 2 years was 21.5% vs 8.0%, and 12.7% vs 5.3% at 3 years. Multivariate analysis of survival among cGBM patients showed that younger age (P < .0001) and having radiation therapy (P < .0001) were significantly associated with reduced hazard of mortality. Among all patients, multivariate analysis showed that tumor location (P = .03), age (P < .0001), tumor size (P = .009), radiation (P < .0001), and resection (P < .0001) were associated with survival time in the unmatched cohort.   
 CONCLUSION Median survival time for cGBM and sGBM patients was 8 months, but cGBM patients had a survival time advantage as the study progressed. These findings suggest that cGBM patients should be treated as aggressively as sGBM patients with surgical resection and radiation therapy.
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