Gliosarcomas account for about 2% (Meis et al. 1990; Galanis et al. 1998; Kozak et al. 2009) of all glioblastoma cases. The annual incidence in North America and Europe is approximately one new case per 1,000,000 (Lantos et al. 1996). Otherwise, the general epidemiology follows that of glioblastoma. The median age at presentation is between 50 and 70 years of age, with the largest study finding a median age of 63 years (Kozak et al. 2009). Like glioblastoma, gliosarcoma patients are slightly more likely to be male (M:F, 1.4–1.8: 1.0) (Morantz et al. 1976; Kozak et al. 2009). Also, similar to other glioblastomas, gliosarcomas are almost always located supratentorially but gliosarcomas specifically have a predilection for the temporal lobe. Kozak et al. (2009) found that approximately 34.0% of gliosarcomas were located in the temporal lobe compared to 23.0% of other glioblastomas.

The clinical presentation of gliosarcoma is similar to that of other rapidly expanding cerebral tumors. Reflecting their location, presenting symptoms of gliosarcomas include headache, weakness, nausea, personality changes and confusion, seizures, and aphasia (Morantz et al. 1976; Perry et al. 1995). Salient signs consist of papilledema, hemiparesis, homonymous hemianopsia, and dysphasia (Morantz et al. 1976). These signs and symptoms correlate strongly to the clinical features of glioblastoma.

Interestingly, in contrast to the majority of glioblastomas, which rarely metastasize outside the cranium, gliosarcomas have a much higher likelihood of hematogenous dissemination to other organs. Han et al. (2009) found that 11% of the reported cases in literature were associated with extracranial metastases. The lungs (72%), liver (41%), and lymph nodes (18%) were most often involved (Beaumont et al. 2007), but gliosarcoma metastases have been reported in a variety of anatomic locations, including adrenal glands, kidneys, skin, oral mucosa, spleen, bone marrow, ribs and spine. Beaumont et al. (2007) reported on one patient who had almost universal spread of disease including to previously unreported organs such as the thyroid, pericardium, myocardium, diaphragm, pancreas and stomach. The past several decades have witnessed an increase in the number of gliosarcoma distant metastasis reports, potentially attributable to both an increased awareness of the diagnosis and the modestly prolonged survival offered by better treatments.

Unfortunately, gliosarcoma is an aggressive disease with dismal outcomes. In fact, overall survival of untreated patients has been reported to be a mere 4 months (Morantz et al. 1976; Kozak et al. 2009). Kozak et al. found that the median survival of all gliosarcoma patients was only 9 months, which is comparable to the median survival found in the smaller retrospective studies. They also found that the prognosis of patients with gliosarcoma was slightly, but significantly, worse than patients with glioblastoma. In addition to receiving treatment, younger age at diagnosis is also associated with a longer median survival. Patients diagnosed before the age of 50 had a median survival of 15 months compared to 7 months for those diagnosed after the age of 50. Furthermore, tumor location has an impact on overall survival; ventricle involvement predicts worse outcomes.