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About Brain Tumors

Nearly 80,000 people, including adults and children, are expected to be diagnosed with primary brain tumor in the United States this year. For information specific to pediatric brain tumors, please click here.

A brain tumor is an abnormal growth of tissue in the brain. The most common surgical treatments are removal via craniotomy or transsphenoidal surgery. Other common surgical treatments include radiosurgery and laser interstitial ablation therapy. In some cases, a tumor may not be amenable to surgical removal, but a surgical biopsy may still be necessary to definitively diagnose the tumor before proceeding with medical treatments.

Depending on a brain tumor’s origin, it is classified as either primary or secondary, and depending on a brain tumor’s behavior, it is classified as either benign or malignant.

A benign tumor does not contain cancer cells and usually, once removed, does not recur. Most benign brain tumors do not invade surrounding tissue and therefore have clear borders; however, these tumors can cause symptoms similar to malignant tumors because of their size and location in the brain. Often, benign tumors can be cured with resection.

Malignant brain tumors contain cancer cells, are usually fast growing and invade surrounding tissue. Malignant brain tumors very rarely metastasize outside of the brain, but they often spread beyond the margins of the resection and thus, may recur after treatment.

The World Health Organization grades tumors on a scale of one to four on the basis of tumor cell appearance and tumor behavior. The higher the grade, the more aggressive and abnormal the tumor. Grade 1 tumors are slow growing and benign, and they do not spread in the brain; Grade 2 tumors are slow growing but the cells have an abnormal appearance and can progress to higher grades over time; Grade 3 tumors are fast growing and malignant; Grade 4, the most malignant and aggressive tumors, are fast growing with highly abnormal cellular appearance. There are also some molecular features that have great influence on prognosis for brain tumors, the most important of which is the mutation of a gene called IDH1.

There are many different types of brain tumors, and they are usually categorized by the type of cell from which the tumor originates. Some tumors are also categorized by the area of the brain where they occur. The most common types of brain tumors include the following:


  • Gliomas, the most common type of primary brain tumor, begin from glial cells. There are several types of gliomas, categorized by where they are found and the type of cells that started the tumor. For information about gliomas, please click here. The following are the different types of gliomas:
    • Astrocytomas are a common type of glioma, and they can be found anywhere in the brain or spinal cord. For information about astrocytomas, please click here. (Astrocytomas in the spine are handled by the specialists at our Spine Hospital. For information about spinal astrocytomas, please click here.)
    • Oligodendrogliomas, which make up about 10 to 15 percent of gliomas, are found commonly in the cerebrum. For information about oligodendrogliomas, please click here.
    • Ependymomas, which are rare and develop mostly in children, arise from ependymocytes. For information about ependymomas, please click here. (Ependymomas in the spine are handled by the specialists at our Spine Hospital. For information about spinal ependymomas, please click here.)
    • Mixed gliomas contain more than one type of glial cell. Mixed gliomas make up about 5 to 10 percent of gliomas.
    • Gangliogliomas develop from both glial cells and nerve cells and are rare.
    • Optic nerve gliomas develop on the astrocytes around the optic nerves, which transmit visual information from the retina at the back of each eye to the brain.
    • Brain stem gliomas are tumors found in the brainstem and occur almost exclusively in children.
    • Cerebellar astrocytoma are tumors that develop in the cerebellum.


  • Meningiomas are usually benign, slow-growing tumors that originate from the meninges and may exist for years before being detected. For information about meningiomas, please click here.


  • Schwannomas are benign, nerve sheath tumors that arise from Schwann cells and are most commonly found on the eighth cranial nerve, which controls hearing and balance. Schwannomas in this location are sometimes also called vestibular schwannomas or acoustic neuromas; for more information on them, please click here.

Pituitary tumors

  • Pituitary tumors are tumors that arise in the pituitary gland and are frequently benign. For information about pituitary tumors, please click here.

Primitive neuroectodermal tumors

  • Primitive neuroectodermal tumors (PNETs) are found in the cerebrum, and when observed under a microscope, they are identical to medulloblastomas. Medulloblastomas differ in the location in which they are found. PNETs are fast-growing and often malignant, with occasional spreading throughout the brain or spinal cord. For information about PNETs, please click here.


  • Medulloblastomas are malignant tumors found near the midline of the cerebellum and can metastasize to other areas of the central nervous system, especially around the spinal cord. For information about medulloblastomas, please click here.


  • Craniopharyngiomas are benign, slow-growing tumors that occur at the base of the brain near or in the pituitary. For information about craniopharyngiomas, please click here.

Pineal region tumors

  • Many different tumors can arise near the pineal gland, including gliomas, meningiomas, germ cell tumors, pineal cell tumors and pineal cysts. For information about pineal region tumors, please click here.

Clival tumors

  • Clival tumors are growths on the base of the skull, specifically the clivus, and are classified as either a chordoma or a chondrosarcoma. For information about clival tumors, please click here.


  • Esthesioneuroblastomas, an extremely rare tumor that develops in the nose, arises from olfactory nerve cells.

The most common brain tumors among adults are secondary brain tumors, also called metastatic brain tumors. These are tumors that begin to grow in another part of the body, then metastasize to the brain through the bloodstream. When the tumors metastasize to the brain, they commonly go to the cerebrum and sometimes to the cerebellum. Often, an individual may have multiple metastatic tumors in several different areas of the brain. Common types of cancer that can travel to the brain include lung cancer, breast cancer, melanoma and colon cancer, all of which are considered malignant once they have spread to the brain.

patient journey

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