III. Primary Neoplasms in Adults

General Characteristics

For all intracranial tumors, about half (more in some studies) are primary tumors; the remainder are metastatic tumors (the numbers depend somewhat on the type of study performed).  Of adult primary brain tumors, astrocytoma and glioblastoma (gliomas) comprise about 80%.  Glioblastoma makes up about half of gliomas.