Brain tumors are either malignant or benign,depending on the cell type.Primary tumors generally do not resemble the carcinomas and sarcomas found elsewhere in the body and rarely metastasize outside the CNS.Both primary and metastatic tumors of the brain and its membranes are included in the term intracranial tumors.What three tumor types are the most frequently seen CNS tumors in adults?

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An estimated 22,070 new brain and other nervous system cancers were estimated to occur in 2009.Brain metastases outnumber primary neoplasms by at least 10 to 1,and they occur in 20% to 40% of cancer patients.When categorized by tumor type,the percentage of occurrence is as follows:glioblastoma 50%,meningioma 17%,astrocytoma 10%,pituitary adenoma 4%,oligodendroglioma 3%,ependymoma 2%,medulloblastoma 2%,neurilemmoma 2%,hemangioma 2%,craniopharyngioma 1%,pinealoma 1%,and sarcoma 1%.

Brain Tumors Are Either Malignant or Benign,depending on the Cell