Brain Tumors in Adults

The anatomy of a healthy adult brain
Some of the basic structures of a healthy adult brain include the lobes, the brainstem, and the cerebellum.

It can be one of the most devastating diagnoses a patient can hear: You have a brain tumor. If you or someone in your family has been diagnosed with a brain tumor, information is your best weapon in the journey you are about to begin. This overview will help you understand brain tumors in adults and will direct you to more detailed information about your specific type of tumor. (This site has a separate section on Brain Tumors in Children; see those pages for information about pediatric tumors.)

Brain tumors are described and identified in several different ways. Some describe the tumor’s location, some describe the behavior of the tumor, and others describe the nature or origin of the tumor.

One way to describe a tumor is by whether it is primary or metastatic:

  • A primary tumor is one that originated in the area in which it is found. The most common type of primary tumor is a glioma, meaning that it originates from the glial cells that surround and support the brain’s nerve cells.
  • A metastatic brain tumor is one that develops as an extension of another cancer (such as lung, breast, colon, or kidney). Most brain tumors in adults are metastatic.


Another way to describe a tumor is by whether it is benign vs. malignant (although this distinction may often times be misleading, as each person’s tumor is highly unique).

  • A benign brain tumor usually has definite borders and clean edges and does not infiltrate into healthy brain tissue. A benign tumor is not cancer, but it’s not necessarily harmless. It may need to be treated if it’s causing symptoms or creating pressure in the brain. The most common benign tumors in adults are meningiomas,  schwannomas (also called acoustic neuromas), and pituitary adenomas.  Hemangioblastomas and craniopharyngiomas are less common benign brain tumors.
  • A malignant tumor is a cancerous growth that spreads and infiltrates into other brain tissue. The most common malignant tumors in adults are gliomas, including glioblastoma multiforme (GBM) – the type of brain tumor that claimed the lives of Senator Edward Kennedy and baseball star Gary Carter.


The line between benign and malignant is not always clear, and some tumors are diagnosed as “anaplastic,” or intermediate.

Another common way to describe a tumor is by its location in the brain. For example, meningeal tumors, also called meningiomas, are located in the meninges (the protective layers under the skull that cover the brain and spinal cord). A meningioma can develop from different types of brain or spinal cord cells. 

Brain tumors may also be described by the nature of the tumor itself:

Gliomas are named for the glial cells from which they grow. About half the cells in the brain are the all-important neurons, which send and receive messages between the brain and every other part of the body; the other half are glial cells that protect, support, and supply nutrients to those neurons.  There are several sub-types of glial cells, with related tumor types:

  • Astrocytomas grow from the star-shaped astrocyte cells. (Glioblastomas are a kind of astrocytoma.)
  • Oligodendrogliomas grow from oligodendrocyte cells.
  • Ependymomas grow from ependymal cells.
  • Schwannomas grow from Schwann cells (these are nerve cells that are in the peripheral nervous system, not the central nervous system, but they are included here because they often develop in the nerves of the head and neck).

Non-glial tumors arise from other brain structures, and include:

  • Craniopharyngiomas develop from the pituitary stalk, which attaches the pituitary gland to the brain; they are found only in that location, above or around the pituitary gland.
  • Meningiomas develop from the meninges — the outer layers of the brain.
  • Embryonal tumors develop when a fetus is first forming. Embryonal tumors include primitive neuroectodermal tumors (PNETs), medulloblastomas, pineal gland tumors, medulloepitheliomas, and ependymoblastomas. They are more common in children than in adults. (See more about Brain Tumors in Children.)

What Causes a Brain Tumor?
Researchers don’t know for sure what causes a brain tumor to develop. Some brain tumors are associated with genetic conditions, such as neurofibromatosis, von Hippel-Lindau disease, Li-Fraumeni syndrome, and retinoblastoma. Some tumors may be caused by genetic mutations, by exposure to environmental toxins, or by previous radiation treatments for other cancers.

At Weill Cornell Medicine Neurological Surgery, our neurosurgeons are highly skilled in the most advanced minimally invasive procedures for treating brain tumors. Our relationship with NewYork-Presbyterian allows our surgeons access to the very best facilities and specialists, as well as the most leading-edge research laboratories, to ensure that patients receive the very best treatment available. In addition to microsurgical techniques, our surgeons employ advanced functional mapping strategies and imaging modalities to maximize removal of the tumor in the safest manner possible. When appropriate, we offer focused, stereotactic radiation therapy in lieu of or in addition to surgery. We also offer many innovative clinical trials, particularly for patients with malignant disease.

Finally, our neuro-oncologists design precision oncologic strategies for patients with brain tumors. We routinely perform molecular and genetic testing on our patient’s brain tumors through the Englander Institute for Precision Medicine. This allows our doctors to offer targeted therapies when possible to allow for the best possible outcomes for our patients.

Use our online form to request an appointment for a consultation or a second opinion.

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See also: Clinical Trials for Brain Tumors

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Reviewed by Rohan Ramakrishna, M.D.
Last reviewed/last updated: December 2020
Illustration by Thom Graves, CMI

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