About Primary Brain Tumors

According to the American Cancer Society, each year approximately 22,000 people in the United States are diagnosed with a brain tumor.

Doctors categorize most brain tumors as being either high grade (rapidly growing) or low grade (slow growing). Because the brain is enclosed in the skull, however, even low-grade tumors can be dangerous. The skull cannot expand to make room for a growing tumor, and a tumor can press on or damage brain tissue. Also, a low-grade brain tumor can behave like, or turn into, a high-grade tumor and become life threatening.

In some cases, cancers that begin in other parts of the body migrate, or metastasize, to the brain. Because these metastatic brain tumors are made of different kinds of cells, they are treated differently than primary brain tumors. Learn more about how we diagnose and treat metastatic brain tumors.

Types of Primary Brain Tumors

Most primary brain tumors are named according to the type of cells from which they arise. There are more than 125 types of brain tumors officially recognized by the World Health Organization.

Gliomas are the most common type of primary brain tumor. They develop from glial cells, which perform a variety of supportive functions in the brain. There are several types of gliomas, which are characterized according to the subtype of cell from which they arise and the aggressiveness of the tumor.  These types include low-grade glioma and the more aggressive glioblastoma.

Glioblastoma is the most common and aggressive type of brain cancer in adults. The tumors arise from the star-shaped astrocyte cells, which provide support to the brain’s nerve cells. Because glioblastomas tend to spread through the brain tissue, they can be difficult to remove.

In recent years, doctors at Memorial Sloan Kettering and elsewhere have begun to recognize distinct molecular subtypes of glioblastomas — insights that may lead to new and targeted treatment approaches.

Primary central nervous system lymphoma (PCNSL) is a type of cancer that develops in the lymphatic system, a network of organs called lymph nodes that carry a fluid called lymph throughout the body. Lymph contains a type of cell called a lymphocyte, which plays an important role in fighting disease and infection.

PCNSL begins when lymphocytes in the brain, spinal cord, meninges, or eye become malignant and start to grow and spread uncontrollably. It is more common in people with compromised immune systems, such as those infected with HIV. Central nervous system lymphoma of the eye is called ocular lymphoma.

Because PCNSL typically spreads to multiple locations within the brain and central nervous system, surgery is typically not an effective treatment. Radiation therapy and chemotherapy are most commonly used to control this type of cancer.

Memorial Sloan Kettering has been a leader in the effort to develop new drugs for the treatment of PCNSL. This includes heading national clinical trials of investigational drugs.

Pineal region tumors arise in cells in and around the pineal gland, a small endocrine gland located deep in the brain that creates the neurotransmitter melatonin. Pineal region tumors can cause symptoms when they interfere with the circulation of cerebrospinal fluid, compress brain tissue, or interfere with the production of hormones. Pineal region tumors can be either low grade or high grade.

There are two main types of pineal region tumors. Germ cell tumors arise in germ cells in the areas surrounding the pineal gland. Pineal cell tumors arise in pineal parenchymal cells within the pineal gland. Gliomas can also arise from glial cells located within the pineal gland.

Surgery to remove the tumor is often the primary treatment for pineal region tumors. Radiation therapy and chemotherapy may also be given after surgery to control some types of tumors.

Pituitary tumors arise in epithelial cells that line the pituitary gland, which interprets signals from the hypothalamus in the brain to control the release of hormones by other glands in the endocrine system. Pituitary tumors can cause excessive secretion of pituitary hormones, leading to a variety of disorders.

The Pituitary and Skull Based Tumor Center at Memorial Sloan Kettering is the only center of its kind in the New York City area. We have expertise in caring for peoples with all types of pituitary tumors. Learn more about our approach to caring for people with pituitary tumors.

Meningiomas arise in the membranes that surround the brain on the inside of the skull. Most meningiomas are benign tumors that grow slowly, although some can become malignant. In approximately 25 percent of patients, meningioma can cause seizures. Treatment for meningioma may involve surgery, radiation therapy, or both.

Acoustic neuroma is a type of benign tumor that arises from Schwann cells, which wrap around peripheral nerves in the ear. These tumors, also called schwannomas, can cause problems with hearing and balance. Most acoustic neuromas grow very slowly, some more rapidly, and others not at all.

As an acoustic neuroma expands, it compresses nearby nerves, blood vessels, and the surface of the brainstem and cerebellum, threatening neurological function. Learn more about our expertise in the treatment of acoustic neuroma.

Risk Factors

There are only two proven environmental risk factors for developing a brain tumor:

  • Exposure of the head to x-rays for the purpose of treating diseases such as cancer. This causes less than 5 percent of brain cancers.
  • A history of disorders of the immune system, including congenital immune deficiencies and AIDS, and the use of immunosuppressive drugs to prevent the rejection of transplanted organs or cells. These conditions increase the risk of primary central nervous system lymphoma.

In addition, certain rare genetic disorders may increase the risk of a brain tumor. These include:

  • Li-Fraumeni syndrome (increases the risk of glioma)
  • von Hippel-Lindau disease (increases the risk of hemangioblastoma)
  • tuberous sclerosis (increases the risk of astrocytoma)
  • neurofibromatosis type 1, also known as von Recklinghausen’s disease (increases the risk of glioma)
  • neurofibromatosis type 2 (increases the risk of acoustic neuroma and meningioma).

While these are risk factors that may increase the risk of a brain tumor, there are also several myths about the causes of brain tumors that have insufficient research evidence to support them. For example, at this time there is no solid data that indicates the use of cell phones — or being exposed to the non-ionizing radiation these phones emit — will cause a brain tumor. Nor have experiencing a head trauma, exposure to petrochemicals, or the consumption of aspartame been scientifically linked to an increased brain tumor risk.

Talk with your doctor if you have any concerns about your risk of a brain tumor.


Different parts of the brain govern different functions of the body. This means that symptoms of a brain tumor are usually related to a tumor’s location rather than its size. Your specific symptoms may also help your doctor identify which kind of brain tumor you have.

Symptoms develop when a tumor destroys or compresses normal brain tissue, the tissues around the tumor swell, or the tumor interferes with the normal flow of fluid around the brain and spinal cord.

Brain tumor symptoms may include:

  • Headaches (these may be subtle or they may present in a pattern that is different from a person’s “usual” headache)
  • Seizures (a sudden, involuntary movement of the muscles)
  • Speech problems (slow speech, difficulties with recalling words, substitution of incorrect words when naming objects, or problems with understanding a conversation or a written text)
  • Weakness, often on one side of the body
  • Imbalance or difficulty walking
  • Impaired vision or a restricted visual field

Symptoms of a brain tumor can often resemble those caused by other diseases. If you are experiencing any of the above symptoms, speak with your doctor.