Brain Tumor Glossary of Terms

Easily explore the meaning of hundreds of medical terms or words, many directly used in brain tumor-related terminology.

Calvarium tumor

Calvarium. One of the bones that makes up the vault of the skull (in humans these are the frontal, 2 parietals, occipital and 2 temporals). A tumor in the area of the calvarium.


A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.

Cancer Antigen 125

A substance that may be found in high amounts in the blood of patients with certain types of cancer, including ovarian cancer. Cancer antigen 125 levels may also help monitor how well cancer treatments are working or if cancer has come back. Also called CA-125.

Cancer Cluster

The occurrence of a larger-than-expected number of cases of cancer within a group of people in a geographic area over a period of time.


Any substance that causes cancer.


The process by which normal cells are transformed into cancer cells.

Case Report

A detailed report of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some demographic information about the patient (for example, age, gender, ethnic origin).

Central Nervous System

The brain and spinal cord. Also called CNS.

Central Nervous System Metastasis

Cancer that has spread from the original (primary) tumor to the central nervous system (CNS). Also called CNS metastasis.

Cerebellar Hemangioblastoma

A benign, slow-growing tumor in the cerebellum (part of the brain at the back of the head), made up of abnormal blood vessel growth. People with von Hippel-Landau disease have an increased risk of developing hemangioblastomas.


Having to do with two structures of the brain, the cerebellum (located at the lower back of the brain) and the pons (located at the base of the brain in front of the cerebellum) and the area between them.


This part of the brain coordinates body movements.

Cerebellum blastoma

Cerebellum: The portion of the brain in the back of the head between the cerebrum and the brain stem. Blastoma: A tumor thought to arise in embryonic tissue. The term "blastoma" is commonly used as part of the name for a tumor as, for examples, in glioblastoma and medulloblastoma (types of brain tumors), hepatoblastoma (a liver tumor), nephroblastoma ( Wilms tumor of the kidney), neuroblastoma (a childhood tumor of neural origin), osteoblastoma (a bone tumor) and retinoblastoma (a tumor of the retina).

Cerebral Achromatopsia

Cerebral achromatopsia is a form of acquired color blindness that is caused by damage to the cerebral cortex of the brain, rather than abnormalities in the cells of the eye's retina. It is most frequently caused by physical trauma, hemorrhage or tumor tissue growth.

Cerebral Hemisphere

One half of the cerebrum, the part of the brain that controls muscle functions and also controls speech, thought, emotions, reading, writing, and learning. The right hemisphere controls the muscles on the left side of the body, and the left hemisphere controls the muscles on the right side of the body.

Cerebrospinal fluid

(CSF) The entire surface of central nervous system is bathed by a cerebrospinal fluid, a clear, colorless fluid. The CSF is contained within a system of fluid-filled cavities called ventricles. The Cerebral Spinal fluid has several functions: 1. Protection: the CSF protects the brain from damage by "buffering" the brain. The CSF acts to cushion a blow to the head and lessen the impact. 2. Buoyancy: because the brain is immersed in fluid, the net weight of the brain is reduced from about 1,400 gm to about 50 gm. Therefore, CSF reduces pressure at the base of the brain. 3. Excretion of waste products: the one-way flow from the CSF to the blood takes potentially harmful metabolites, drugs and other substances away from the brain. 4. Endocrine medium for the brain: the CSF serves to transport hormones to other areas of the brain. Hormones released into the CSF can be carried to remote sites of the brain where they may act.

Cerebrospinal Fluid Diversion

The fluid that flows in and around the hollow spaces of the brain and spinal cord, and between two of the meninges (the thin layers of tissue that cover and protect the brain and spinal cord). Cerebrospinal fluid is made by tissue called the choroid plexus in the ventricles (hollow spaces) in the brain. Also called CSF.


The main portion of the brain occupying the upper part of the cranial cavity.

Charged-particle Radiation Therapy

A type of external radiation therapy that uses a special machine to make invisible, high-energy particles (protons or helium ions) that kill cancer cells. This type of radiation may cause less damage to nearby healthy tissue than radiation therapy with high-energy x-rays.

Chelating Agent

A chemical compound that binds tightly to metal ions. In medicine, chelating agents are used to remove toxic metals from the body. They are also being studied in the treatment of cancer.


A procedure in which the blood supply to the tumor is blocked surgically or mechanically and anticancer drugs are administered directly into the tumor. This permits a higher concentration of drug to be in contact with the tumor for a longer period of time.


Chemotherapy combined with immunotherapy. Chemotherapy uses different drugs to kill or slow the growth of cancer cells; immunotherapy uses treatments to stimulate or restore the ability of the immune system to fight cancer.


The use of drugs, vitamins, or other agents to try to reduce the risk of, or delay the development or recurrence of, cancer.

Chemoprevention Study

In cancer prevention, a clinical trial that studies whether taking certain medicines, vitamins, minerals, or food supplements can prevent cancer. Also called agent study.


A quality of some drugs used in cancer treatment. Chemoprotective agents protect healthy tissue from the toxic effects of anticancer drugs.


Treatment that combines chemotherapy with radiation therapy. Also called chemoradiotherapy.


Treatment that combines chemotherapy with radiation therapy. Also called chemoradiation.


The susceptibility of tumor cells to the cell-killing effects of anticancer drugs.

Chemosensitivity Assay

A laboratory test that measures the number of tumor cells that are killed by a cancer drug. The test is done after the tumor cells are removed from the body. A chemosensitivity assay may help in choosing the best drug or drugs for the cancer being treated.

Chemosensitivity testing

A lab test in which a piece of the tumor is sent to the lab to be grown in a test tube. It is exposed to many drugs, in an attempt to find the drug that works the best on your particular tumor type.


A drug that makes tumor cells more sensitive to the effects of chemotherapy.

Chemotherapeutic Agent

A drug used to treat cancer.


Chemotherapy employs the use of drugs to stop or control the growth of cancer cells. The goal of chemotherapy is to kill as many of the tumor cells as possible and to put remaining tumor cells into a non-dividing, sleeping state for as long as possible.

Choroid plexus papilloma

A Choroid plexus papilloma (CPP) is a rare, slow-growing, histologically benign tumor that is commonly located in the ventricular system of the choroid plexus. It may obstruct the cerebrospinal fluid flow, causing increased intracranial pressure. It most commonly affects young children under the age of 5. If it undergoes malignant transformation it is called if is called a choroid plexus carcinoma.


A disease or condition that persists or progresses over a long period of time.

Clinical Practice Guidelines

Guidelines developed to help health care professionals and patients make decisions about screening, prevention, or treatment of a specific health condition.

Clinical Researcher

A health professional who works directly with patients, or uses data from patients, to do research on health and disease and to develop new treatments. Clinical researchers may also do research on how health care practices affect health and disease.

Clinical Study

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called clinical trial.

Clinical Trial

An experimental treatment. There are various types - click here for details. the advantage to brain tumor patients is that some of the most promising treatments are only available in clinical trials.


The brain and spinal cord. Also called central nervous system.

Communicating hydrocephalus

Hydrocephalus is the condition where the fluid spaces in the brain (Ventricles) become enlarged. One of the three basic types is known as Communicating Hydrocephalus. This is a condition where the Cerebro-Spinal Fluid (CSF) inside of the ventricles communicates or is open to, the fluid spaces surrounding the brain. This type usually occurs as a result of some sort of dysfunction of the absorption channels known as the Arachnoid Villi.

Compassionate Use Trial

A way to provide an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments are not available. Compassionate use trials allow patients to receive promising but not yet fully studied or approved cancer therapies when no other treatment option exists. Also called expanded access trial.

Computed Tomography Scan (CT or CAT scan)

This CT reveals brain abnormalities. Simply, this is a sophisticated X-ray machine linked to a computer to create two-dimensional images. It is painless and can be completed in 10 minutes or less. Occasionally a special dye is injected into the bloodstream to provide more detail.


Occurring or existing at the same time as something else. In medicine, it may refer to a condition a person has or a medication a person is taking that is not being studied in the clinical trial he or she is taking part in.


A condition or trait present at birth. It may be the result of genetic or non-genetic factors.

Continuum of Care

In medicine, describes the delivery of health care over a period of time. In patients with a disease, this covers all phases of illness from diagnosis to the end of life.


A symptom or medical condition that makes a particular treatment or procedure inadvisable because a person is likely to have a bad reaction. For example, having a bleeding disorder is a contraindication for taking aspirin because treatment with aspirin may cause excess bleeding.


Having to do with the opposite side of the body.

Control Group

In a clinical trial, the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works.

Controlled Clinical Trial

A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all.

Controlled Study

An experiment or clinical trial that includes a comparison (control) group.


A benign brain tumor that may be considered malignant because it can damage the hypothalamus, the area of the brain that controls body temperature, hunger, and thirst.


An operation in which an opening is made in the skull.


The fluid that flows in and around the hollow spaces of the brain and spinal cord, and between two of the meninges (the thin layers of tissue that cover and protect the brain and spinal cord). CSF is made by tissue called the choroid plexus in the ventricles (hollow spaces) in the brain. Also called cerebrospinal fluid.

Cultured Cell

A human, plant, or animal cell that has been adapted to grow in the laboratory. Cultured cells may be used to diagnose infections, to test new drugs, and in research.

Cultured Cell Line

Cells of a single type (human, animal, or plant) that have been adapted to grow continuously in the laboratory and are used in research.


A sac or capsule in the body. It may be filled with fluid or other material.


Surgery to remove all or part of the bladder (the organ that holds urine) or to remove a cyst (a sac or capsule in the body).


A condition in which there is a lower-than-normal number of blood cells.


The fluid inside a cell but outside the cell's nucleus. Most chemical reactions in a cell take place in the cytoplasm.



Cytotoxic Chemotherapy

Anticancer drugs that kill cells, especially cancer cells.