Brain tumor glossary

A doctor who performs surgery on the brain, spine, and nervous system. They remove tumors, take biopsies, and manage surgical complications related to brain tumors.

A doctor who specializes in diagnosing and managing tumors of the brain and spinal cord. They focus on non-surgical treatments like chemotherapy and symptom management. Unlike neurosurgeons, they may not perform surgery but do have training in neurology and oncology.

A doctor who uses targeted radiation to treat cancer. For brain tumors, they design treatments that destroy tumor cells while protecting healthy brain tissue.

A doctor who treats cancer with medications like chemotherapy, immunotherapy, or targeted therapy. They may be involved in treating brain tumors, especially if the tumor is aggressive or has spread.

A coordinated group of healthcare professionals from different specialties—such as surgeons, oncologists, and nurses—who work together to plan and deliver your care.

A group of medical specialists who meet to review complex cases and recommend the best treatment plan based on their combined expertise.

A general term for tumors that start in glial cells, which support brain function. Includes several subtypes below.

• Glioblastoma (GBM) – A fast-growing and aggressive type of glioma; the most common malignant brain tumor in adults.
• Astrocytoma – A tumor that starts in star-shaped glial cells (astrocytes). Can range from slow-growing (low grade) to fast-growing (high grade).
• Oligodendroglioma – A slower-growing glioma that begins in cells called oligodendrocytes, which support nerve cells.
• Ependymoma – A rare tumor that starts in the lining of the brain’s ventricles or spinal cord. More common in children but can occur in adults.
• Meningioma – A usually benign (non-cancerous) tumor that forms in the meninges, the protective layers around the brain and spinal cord. Can cause symptoms based on location and size.
• Medulloblastoma – A fast-growing tumor that starts in the cerebellum, which controls balance and coordination. Most common in children.
• Pituitary tumor (adenoma) – A growth in the pituitary gland, which controls hormones. Often benign but can affect hormone levels or vision.
• Schwannoma – A tumor that develops from Schwann cells, which insulate nerves. The most common type is vestibular schwannoma (also called acoustic neuroma), affecting hearing and balance.
• Craniopharyngioma – A rare, benign tumor near the pituitary gland. More common in children and can affect growth, hormones, or vision.
• Pineal region tumor – Tumors that occur near the pineal gland, deep in the brain. Includes several rare types, both benign and malignant.

These occur when cancer cells from another part of the body spread to the brain. Common sources include:

• Lung cancer
• Breast cancer
• Melanoma (skin cancer)
• Kidney cancer
• Colon cancer

Metastatic brain tumors are more common than primary brain tumors in adults and may appear as one or multiple tumors in the brain.

A detailed imaging test that shows the structure of the brain and helps doctors detect tumors, their size, and exact location. MRI is also commonly used throughout treatment and follow-up to monitor for tumor progression or brain tumor recurrence (whether the tumor is growing or coming back).

A fast imaging test that can reveal bleeding, swelling, or large brain tumors. It’s often used in emergency situations.

An imaging test that shows how active a brain tumor is by measuring how it uses energy. This helps doctors understand if the tumor is likely to be cancerous or how it’s responding to treatment.

A way to describe how abnormal the tumor cells look under a microscope and how quickly they are likely to grow. Grades range from I (slow-growing) to IV (fast-growing and aggressive).

While most brain tumors don’t “spread” in the same way as other cancers, staging helps determine whether the tumor has grown into nearby brain areas or, in rare cases, spread to other parts of the body.

A procedure where a small piece of the brain tumor is removed, usually during surgery or with a needle, so doctors can examine it under a microscope to confirm the diagnosis and determine the tumor type and grade.

Controls thinking, planning, and personality; tumors may affect behavior.

Involved in memory and hearing; tumors may affect speech or comprehension.

Processes sensory information; tumors may affect spatial awareness.

Processes visual information; tumors may cause vision changes.

Controls breathing, heart rate, and basic life functions.

Helps control movement, balance, and coordination.

A small gland deep in the brain; tumors here are rare but complex.

The small space in the skull near the brainstem and cerebellum.

Removes all or part of the brain tumor to relieve pressure, confirm diagnosis, or prepare for other treatments. The goal is to take out as much tumor as safely possible.

Uses focused high-energy beams to destroy tumor cells. Often used after surgery or when surgery isn’t possible.

Uses drugs to kill or slow the growth of tumor cells. Can be given by mouth, IV, or placed directly into the brain.

Boosts the body’s immune system to help it recognize and attack brain tumor cells.

Uses drugs designed to block specific mutations or features found in some brain tumors, slowing their growth.

A research study testing new treatments that may not be widely available yet. Brain tumor trials can offer access to cutting-edge care. Learn more about brain tumor clinical trials.

A type of radiation therapy placed inside the brain, at the time of surgery. Small collagen tiles that give off radiation are placed where the tumor was removed. Because the radiation starts from inside the brain and moves outward, it targets the area most at risk for tumor regrowth while limiting damage to healthy brain tissue. GammaTile starts working right away, with no need to wait for surgery to heal.¹

A form of radiation given in 1 to 5 sessions. It’s not surgery, but rather high-dose radiation delivered from a machine outside your body. The radiation travels through healthy brain tissue to reach the tumor. Because it’s external, treatment usually starts 2 to 4 weeks after surgery so your brain can heal first.

• Gamma Knife^® – A type of SRS that uses focused beams of radiation to treat small brain tumors. Often done in just one session.
• CyberKnife^® – Another type of SRS that uses a robotic arm to deliver radiation from many angles.
• Proton therapy – A more targeted form of radiation that uses proton particles instead of X-rays.

A type of external beam radiation given over several weeks. Like SRS, IMRT comes from a machine outside the body and must go through healthy tissue to reach the tumor. Treatment usually starts a few weeks after surgery to give your brain time to heal.

Radiation that treats the entire brain. Often used when cancer has spread to multiple spots in the brain. Because it affects more brain tissue, it may cause more side effects than focused treatments like GammaTile, SRS or IMRT.