Brain Tumour 101: A Glossary Of Commonly Used Medical Terms

Gamma Knife surgery - brain scan

Being diagnosed with a brain tumour can be a confusing and overwhelming time for both patients and families. There is a steep learning curve and you may be presented with a lot of unfamiliar medical terms. Here’s a glossary of some of the most commonly used terms to help you make sense of a brain tumour diagnosis and treatment.


The stage where brain tumour cells are dividing rapidly and bear little or no resemblance to normal cells in appearance or function.


An antibody is a protein made by white blood cells that attaches itself to an antigen and neutralises or destroys foreign cells such as viruses or cancer cells.


Antigen is a substance that is recognised by antibodies and induces an immune response.


Benign is usually used to describe a slow-growing tumour that stays in its primary location without spreading to other parts of the body, and they are usually non-cancerous.


A biopsy is a form of neurosurgery that is used to take a sample of cells or tissues for diagnostic purposes.

Blood-brain barrier

The blood-brain barrier is a protective membrane that surrounds the blood vessels within the brain to protect it from circulating blood that may contain toxins and damage brain tissues.


When cancer is treated with drugs to stop the growth of tumour cells, it is called chemotherapy. There are a very limited number of chemotherapy drugs available to treat brain tumours because they are not able to cross the blood-brain barrier.

Gamma Knife surgery

Despite its name, Gamma Knife surgery is not a traditional surgery that involves incisions into the brain. It is a type of stereotactic radiosurgery that is used to deliver precisely focused radiation beams directed to the treatment area in the brain. This deliberately damages the targeted cells, whilst having minimal impact on the surrounding tissues.

High grade tumour

A high-grade tumour is a grade 3 or 4 tumour that is likely to grow and spread quickly to nearby tissue. Depending on the size and location of the tumour, they can be difficult to treat.

The grades are made on the basis of a biopsy specimen that is analysed by a pathologist.

Low grade tumour

A low-grade tumour is a grade 1 or 2 tumour that grows slowly. A grade 1 tumour is unlikely to spread to nearby tissues. A grade 2 tumour may spread and has the potential to regrow even if it is surgically removed.

Metastatic brain tumour

A metastatic brain tumour is a secondary brain tumour that began elsewhere in the body and spread to the brain.


An oncologist is a doctor who specialises in the diagnosis and treatment of cancer. Oncologists who specialise in the treatment of brain tumours are referred to as neuro-oncologists.


Radiotherapy is the use of radiation to manage or kill brain tumour cells. It can be used in combination with other treatments such as chemotherapy and surgery.