Adult brain tumour types
There are over 130 types of brain tumour, as classified by the World Health Organisation (WHO).
Brain tumours differ in terms of the cells they originate from, how quickly they are likely to grow and spread, and the part of the brain they affect. Knowing the type of tumour you have will therefore help you understand your condition.
As a general rule, brain tumours are named according to the type of cell they originate from. Information about the most common brain tumour types can be found below.
What Are Brain tumours?
Let’s start at the beginning – what is a brain tumour?
A brain tumour is a mass of abnormal cells growing in the brain. If the cells come from the brain itself or from its lining it is called a primary brain tumour. If the cells are identified as being from other places in the body it is a secondary or metastatic brain tumour. Primary brain tumours can be benign or malignant. Secondary or metastatic brain tumours are always malignant.
A benign (or non-malignant) brain tumour does not contain cancer cells. It typically grows slowly with clearly defined borders and does not spread to other parts of the brain. However benign tumours can still be life threatening depending on their location in the brain, and they have the potential to develop into higher-grade tumours.
A malignant brain tumour contains cancer cells. It grows more rapidly, often without clearly defined borders, and can invade surrounding brain tissue, although it rarely spreads outside the brain or spine.
Every person’s brain tumour is different. They grow in different areas of the brain, from different cell types, and may have different treatment options. The size of a brain tumour doesn’t matter nearly so much as where it is located. A large, benign tumour may be easily accessible and therefore easy to remove surgically. Or you can have a pea–sized tumour that is critically placed, and so makes surgery very difficult. Each case needs to be reviewed, discussed, and options explored. It’s complex!
Click on the above image or below link to read the comic What Are Brain Tumours?
What causes a brain tumour?
The causes of most brain tumours are currently unknown, so there are no known prevention measures. Some genetic disorders may mean that some people are predisposed to getting a brain tumour and there is the suggestion that some environmental factors may increase our risk, but research into the causes of brain tumours is ongoing.
Grading brain tumours
The World Health Organisation has developed a classification and grading system for brain tumours. Knowing the classification and grade of an individual tumour helps to predict its likely behaviour. The tumour grade ranges from 1 to 4 and represents how fast the cells can grow and are likely to spread.
Grade 1 — the tumour grows slowly, has cells that look like normal cells, and rarely spreads into nearby tissues. It may be possible to remove (resect) the entire tumour by surgery, but tumours in the brain stem cannot be completely resected safely.
Grade 2 — the tumour grows slowly, but may spread into nearby tissue and may recur (come back). Some tumours may become a higher grade tumour.
Grade 3 — the tumour grows quickly, is likely to spread into nearby tissue, and the tumour cells look very different from normal cells.
Grade 4 — the tumour grows and spreads very quickly and the cells do not look like normal cells. There may be areas of dead cells in the tumour. Grade 4 brain tumours are harder to manage than lower grade tumours. High-grade tumours can be difficult to treat.
If the tumour contains a mix of cells with different grades, the highest (most malignant) grade will be used to define the entire tumour.
non-malignant tumours
A non-malignant tumour is a mass of cells that grows relatively slowly in the brain and is non-cancerous. Sometimes these brain tumours are classified as ‘benign’ (we don’t like the word benign as the impact of any brain tumour diagnosis is anything but benign – we would urge you to ask your doctor to say ‘non-malignant’ instead).
Here is a list of some but not all non-malignant brain tumours and a little bit about them (for more information please speak to your doctor or refer to our online resources).
Meningioma
Meningiomas are tumours that start in the layers of tissue (meninges) that cover the brain and spinal cord. They are the most common brain tumour in adults accounting for about one third of all adult brain tumours. They usually grow slowly and may exist for many years without being detected. They can often be removed safely with surgery. Sometimes observation is the best approach if there are no symptoms. Most meningiomas are considered non-malignant (benign) or low grade tumours. However, unlike non-malignant tumours elsewhere in the body, some of these brain tumours can cause disability and may sometimes be life threatening. The WHO classification divides meningiomas into three grades:
Grade 1: Benign - the most common type of meningioma
Grade 2: Atypical - slow growing meningioma with a higher risk of recurring, sometimes as a higher grade
Grade 3: Atypical/Malignant - fast growing but rare tumours that are highly likely to recur
Pituitary tumours
The pituitary gland makes and releases hormones into the bloodstream. Most pituitary tumours are non-malignant. Non-malignant pituitary gland tumours are also called pituitary adenomas. These tumours are generally divided between those that release more hormones and those that do not. Tumours that do not release hormones are known as non-functioning adenomas and are generally picked up incidentally on brain imaging scans or when they grow large enough to cause headaches or visual changes. Functioning pituitary adenomas release hormones which cause symptoms relating to the effects of having increased amounts of that particular hormone in the body (i.e. prolactin, ACTH, growth hormones). Treatment options depend on the type of pituitary tumour, but surgery is the most common treatment.
Acoustic neuroma - (Also called vestibular schwannoma)
Acoustic neuroma (also called vestibular schwannoma) is a non-malignant tumour which develops from Schwann cells. These are fatty cells on the outside of nerves. Usually, vestibular schwannomas start in the Schwann cells on the outside of the vestibulocochlear nerve. The vestibulocochlear nerve connects the brain to the ear. It controls hearing and balance. Acoustic neuromas constitute less than 5% or all brain tumours. They can be tricky - if completely removed they usually don't recur, but there can be several complications from surgery, which can include facial weakness, hearing loss, dizzyness and headaches.
Craniopharyngioma
Craniopharyngioma – a rare tumour that grows in the region of the optic nerve and hypothalamus, near the base of the brain. They are more common in children than adults. Whilst it is benign it can cause problems and treatment options depend on how much it is impacting on the person.
Pilocytic astrocytoma
Pilocytic astrocytoma – the most non-malignant type of astrocytoma which occurs primarily in children and adolescents. Treatment depends on position.
Colloid cyst
Colloid cyst – these are curable lesions, which occur almost exclusively in adults in an area of the brain known as the third ventricle. They are best treated by surgical removal where possible.
Hemangioblastoma
Hemangioblastoma – a rare non-malignant tumour composed of cells from the lining of the blood vessels. These can usually be removed through surgery.
Epidermoid cyst
Epidermoid cyst – these are tumours which are really just pieces of skin enclosed in the brain due to a mistake in fetal development. You sometimes hear stories in the press about a foot being found in a brain – this would be an epidermoid cyst. Surgery is usually for first course of action to remove as much as is possible.
Malignant tumours and tumours with uncertain behaviour
Here is a list of some but not all malignant brain tumours and a little bit about them (for more information please speak to your doctor or refer to our online resources).
Glioma
Glioma – A catch all term for a range of brain tumours. These tumours arise from glial cells (support cells of the brain) and can be non-malignant or malignant. Most gliomas arising in adults fall under a general term of adult-type diffuse gliomas while in children, they fall under either paediatric-type diffuse low grade gliomas or paediatric-type diffuse high grade gliomas.
Astrocytoma IDH-mutant
Astrocytomas arise from star-shaped glial cells called astrocytes or cells that appear similar to astrocytes under the microscope having arisen from cells that can become astrocytes (precursors). In adults, astrocytomas most often arise in the cerebrum. In children, they occur in the brain stem, the cerebrum, and the cerebellum. Astrocytomas have a mutation in the IDH gene, and can range between grade 2-4 depending on histological (tissue structure and appearance under the microscope) features. Grade 3 astrocytomas were previously known as anaplastic astrocytomas but the 2021 WHO classification has stopped using terms such as 'anaplastic' and 'atypical' in favour of numerical grading (i.e. grade 3). Grade 4 astrocytomas were also known as glioblastomas but glioblastomas are now seen as a distinct entity from astrocytomas and have different genetic changes (no mutation in the IDH gene).
Oligodendroglioma - IDH-mutant, 1p/19q-codeleted
Oligodendrogliomas are rare tumours that arise from cells that make the fatty substance that covers and protects nerves. These tumours usually occur in the cerebrum. They grow slowly and usually do not spread into surrounding brain tissue. They are most common in young to middle-aged adults. The best treatment is to remove as much as possible and then treat with further therapies if it begins to grow. These tumours can be grade 2 or 3 depending on histological features. Please note that grade 3 oligodendrogliomas were previously known as anaplastic oligodendrogliomas but are now referred to as grade 3 oligodendrogliomas (in favour of numerical grading).
Glioblastoma, IDH-wild type
Previously known as glioblastoma multiforme or grade IV astrocytoma, this tumour is now known as glioblastoma. Glioblastoma or GBM - is the most common malignant, primary brain tumour in adults. These grade 4 tumours develop in the cerebral hemisphere and spread quickly into the surrounding brain. They are different to astrocytomas as they do not have a mutation in the IDH gene. They can be treated with a range of treatments, including surgery, radiation and chemotherapy. The treatment goal with a GBM is to relieve the pressure created and to make the surrounding area unfavourable for continued growth.
Ganglioglioma
Ganglioglioma – this is mixed cell glioma and the best chance of a cure is complete resection. If the tumour grows back then further therapies are recommended.
Ependymoma
Ependymoma – the tumour arises from cells that line the ventricles or the central canal of the spinal cord. They are most commonly found in children and young adults. Surgical removal of as much of the tumour as is possible is recommended, followed by radiation to prevent the spread of cells through the spinal column.
Lymphoma
Lymphoma – Tumours of unknown origin which can appear spontaneously or in a patient whose immune system is compromised. They resemble gliomas and are usually treated with radiation and chemotherapy.
Medulloblastoma
Medulloblastoma – This tumour usually arises in the cerebellum. It is the most common brain tumour in children, particularly in ages of 5 to 9 years. The more that can be removed the better. Chemotherapy and craniospinal radiation may be used post surgery. A primitive neuroectodermal tumour resembles a medulloblastoma in appearance and has the same treatment options.
Germ cell tumour
Germ cell tumours – there are subdivisions of this tumour. Most are treated with surgery, radiation and chemotherapy. The tumour arises from a germ cell and most germ cell tumours that arise in the brain occur in people younger than 30.
Pineoblastoma/pineocytoma
Pineoblastoma/pineocytoma – These rare brain tumours (but more common in children) arise in or near the pineal gland. The pineal gland is located between the cerebrum and the cerebellum. Pineal tumours are classified as either pineocytomas (grade II) that grow slowly or pineoblastomas (grade IV) which are more aggressive. Treatment options include surgery followed by radiation and chemotherapy.
Chordoma/chondrosarcoma
Chordoma/chondrosarcoma – slow growing tumours are most often detected in young adults. They rarely mestatasize and rarely cause symptoms. Surgery and radiation are the preferred treatment options.
Choroid-plexus carcinoma
Choroid-plexus carcinoma – rare tumours which occur in the ventricles in children. Surgery is the preferred treatment, followed by radiation.