Astrocytomas are the most common type of primary brain tumour within the group of brain tumours called gliomas. Primary means they have originated from the brain instead of spreading from elsewhere. About one third of all brain tumours diagnosed in the UK are astrocytomas.

They grow from a type of cell in the brain called an astrocyte, which is the most abundant cell in the brain. They support and protect the neurons (nerves) and help to pass messages between them. Astrocytes, therefore, are vital in processing information in the brain.

What causes an astrocytoma?

There is nothing you could have done, or avoided doing, that would have prevented you from developing a brain tumour.

As with most brain tumours, the cause is not known. Research into possible causes is focussing around our genes.

Our genes control the way our cells grow and divide. Mutations (changes) in our genes can cause this process to go wrong, resulting in the cells growing uncontrollably and forming a tumour. These changes are often the result of a mistake being made when the cell copies its DNA before dividing.

Read more about how brain tumours are formed.

Types of astrocytoma

Brain tumours (or tumors as they are known internationally) are graded from 1 - 4, according to what they look like under the microscope and how they are likely to behave. This means how fast they grow and how likely they are to spread.

Diagram of main parts of the brain

Astrocytomas can be any grade:

Astrocytoma Grade 1 (Pilocytic astrocytomas)

Grade 1 astrocytomas are called 'pilocytic astrocytomas'. Pilocytic means the cells are elongated and hair like.

They are slow growing, relatively contained and unlikely to spread to other parts of the brain. They are also unlikely to return after being surgically removed.

The are most often found in children and young adults under the age of 20 and are equally common in males and females. They are very rare in adults over 50 years.

They tend to grow in the cerebellum, which controls balance. They can also occur in the optic pathways, which are involved in sight.

Pilocytic astrocytomas occur in around 10% of people who have 'neurofibromatosis type 1' (NF1). This is a genetic condition you are born with that causes tumours to grow along your nerves.

Astrocytoma Grade 2 (Diffuse astrocytoma)

The most common grade 2 astrocytoma is called a 'diffuse astrocytoma'. Diffuse means it does not have well-defined edges, which can make it more difficult to remove completely. They are slow-growing, but can sometimes return, following treatment, as a grade 3 astrocytoma.

They occur most often in adults between the ages of 20 and 45. They are more common in males than females.

Astrocytoma Grade 3 (Anaplastic astrocytoma)

A grade 3 astrocytoma is called and 'anaplastic astrocytoma'. Anaplastic means the cells divide rapidly and do not resemble normal cells in structure or function.

They are fast-growing and often referred to as 'malignant' or cancerous. They often recur following treatment in a more advanced form i.e. grade 4 astrocytoma (glioblastoma).

They are more common in adults between the ages of 30 and 70 and are more common in males.

Astrocytoma Grade 4 (Glioblastoma)

Grade 4 astrocytomas are usually called glioblastoma. You may hear them called glioblastoma multiforme, or GBM for short.

Find out more about Glioblastoma

Other brain tumours, which don't have astrocytoma in their name, are also actually astrocytomas as they grow from astrocytes. For example, some types of DIPG (Diffuse Intrinsic Pontine Glioma).

How are astrocytomas treated?

The treatment for astrocytomas depends on the grade of the tumour, as well as its size and location:

Grades 1 & 2

Treatment in adults is normally surgery to remove as much of the tumour as safely possible. How much will depend on where it is in the brain. If completely removed, this is called 'total or complete resection'.

At this point, you may be told about, or may like to ask about, 'biomarker testing' and biobanking.

More treatment may not be needed, but you will be regularly monitored with MRI scans. This is called 'watch and wait', where no treatment is given, unless your tumour changes or grows, or your symptoms worsen.

If the tumour cannot be completely removed, the surgeon will remove as much as possible. This is known as 'debulking' or 'partial resection'. This is more likely the case with Grade 2 astrocytomas whose edges are less well defined.

You may also be given radiotherapy to kill off any tumour cells that could not be reached during surgery. Again, this is more likely to be needed with Grade 2 tumours.

Occasionally, chemotherapy may also be given. For children, chemotherapy, rather than surgery, is often the first line of treatment. Doctors try to avoid giving radiotherapy to children under 3.

Grade 3

As these tumours are faster growing and more likely to spread, the usual course of treatment is surgery followed by radiotherapy and sometimes chemotherapy.

The course of radiotherapy may be over several weeks. Radiotherapy is very rarely used in children under 3 years.

For chemotherapy, the drug temozolomide is often used. Alternatively, in adults, another chemotherapy drug, carmustine, may be put into a 'wafer' and put directly into the brain during surgery. The carmustine will be gradually released as the wafer dissolves over 2 -3 weeks.

Grade 4

Grade 4 astrocytomas are usually referred to by the term glioblastoma. You may sometimes hear them called glioblastoma multiforme, or GBM for short, though these terms are less used nowadays.

Find out more about Glioblastoma

Read more about the treatment options for Astrocytoma

Watch and wait

Sometimes no initial treatment is given - learn why and get tips on how to cope.


Learn about the types of surgery you may have and why surgery is not possible for everyone.


Find our how chemotherapy drugs destroy tumour cells by disturbing their growth.


Find out how radiotherapy destroys tumour cells whilst causing as little damage as possible to surrounding cells.

Information and support

Whether you've been diagnosed with a brain tumour, or it's a family member or friend, we are here to help. We offer a wide range of inclusive and accessible information and services for everyone affected by a brain tumour, whether it's low or high grade, adult or child.

Living with a brain tumour

Find information on side-effects, managing finances and caring for someone with a brain tumour.

Get Support

If you need advice or just someone to talk to find out about our phone support lines, local and online support groups.


Information about the prognosis (likely outcome) for specific types of brain tumour.

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