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, includ ing low-grade diffuse fibrillary and pilocytic astrocytomas, oligodend rogliomas, and mixed oligo-astrocytomas, and high-grade diffuse fibril lary astrocytomas, oligodendrogliomas, and mixed oligo-astrocytomas. M ethods: Utilizing the St. Anne-Mayo (SAM) grading system, the incidenc e, patient characteristics, and survivals of 196 patients with low-gra de (SAM grade 1 + 2) and 318 patients with high-grade (SAM 3 + 4) supr atentorial tumors were compared. Results: Among low-grade tumors, most favorable were 5- and 10-year survival rates for patients with pilocy tic astrocytomas, which were 85% and 79%, respectively. Median surviva l and 5- and 10-year survival rates for the other low-grade tumors wer e lower, and were proportionately improved by the presence of an oligo dendroglial component: diffuse fibrillary astrocytomas - 4.7 years, 46 %, and 17%, oligodendroglioma 9.8 years, 73%, and 49%; and mixed olig o-astrocytoma - 7.1 years, 63%, and 33%, respectively. For high-grade tumors, patients with either oligodendrogliomas or mixed oligo-astrocy tomas had comparable favorable survivals in comparison to diffuse fibr illary astrocytomas. Median survivals and 5- and 10-year survival rate s were 4.5 years, 45%, and 15% for the oligodendrogliomas and mixed ol igo-astrocytomas versus 0.8 years, 3%, and 0% for the diffuse fibrilla ry astrocytomas, respectively. Conclusion: These survival data suggest that both low-grade and high-grade supratentorial gliomas have outcom es which are highly dependent upon histologic type.