Prognosis of cerebellar glioblastomas: correlation between prognosis and immunoreactivity for epidermal growth factor receptor compared with supratentorial glioblastomas.

BACKGROUND Cerebellar glioblastomas (GBM) are rare tumors whose clinicopathological characteristics are not well understood. PATIENTS AND METHODS Clinico-immunohistochemical findings were retrospectively analyzed in 43 supratentorial- and 7 cerebellar GBM. The correlation between survival and immunopositivity for p53, epidermal growth factor receptor (EGFR) and Ki-67 in these tumors was statistically analyzed and compared. RESULTS Of the 43 patients with supratentorial GBM, 27 (62.8%) were EGFR immunopositive; their survival was significantly shorter than that of the 16 EGFR-negative patients (p=0.0248). There was no significant correlation between survival and p53 immunopositivity (p=0.7870) and Ki-67 labeling index (p =0.7133). All 5 cerebellar GBM patients treated with radio- and chemotherapy were EGFR-immunonegative; they survived significantly longer than patients with supratentorial GBM (p=0.0296) possibly because their EGFR negativity rendered their tumors more highly radiosensitive. CONCLUSION The better prognosis of patients with cerebellar, EGFR-negative tumors compared to patients with supratentorial tumors is due to the higher radiosensitivity of these tumors.