Supratentorial gliomas: A comparative study by grade and histologic type

Purpose: To try and identify biologic differences based on tumor grade and histologic type between the major classes of glial tumors, including low-grade diffuse fibrillary and pilocytic astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas, and high-grade diffuse fibrillary astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas. Methods: Utilizing the St. Anne-Mayo (SAM) grading system, the incidence, patient characteristics, and survivals of 196 patients with low-grade (SAM grade 1 + 2) and 318 patients with high-grade (SAM 3 + 4) supratentorial tumors were compared. Results: Among low-grade tumors, most favorable were 5- and 10-year survival rates for patients with pilocytic astrocytomas, which were 85% and 79%, respectively. Median survival and 5- and 10-year survival rates for the other low-grade tumors were lower, and were proportionately improved by the presence of an oligodendroglial component: diffuse fibrillary astrocytomas - 4.7 years, 46 %, and 17%, oligodendroglioma 9.8 years, 73%, and 49%; and mixed oligo-astrocytoma - 7.1 years, 63%, and 33%, respectively. For high-grade tumors, patients with either oligodendrogliomas or mixed oligo-astrocytomas had comparable favorable survivals in comparison to diffuse fibrillary astrocytomas. Median survivals and 5- and 10-year survival rates were 4.5 years, 45%, and 15% for the oligodendrogliomas and mixed oligo-astrocytomas versus 0.8 years, 3%, and 0% for the diffuse fibrillary astrocytomas, respectively. Conclusion: These survival data suggest that both low-grade and high-grade supratentorial gliomas have outcomes which are highly dependent upon histologic type.