What is a DIPG brain tumour

Expert / 3 July, 2024 / Ellie Thompson

My Baba’s Editor, Ellie Thompson, recently lost her beautiful four-year-old boy, Billy, to a DIPG brain tumour. Ellie asked the experts at The Brain Tumour Charity to outline exactly what a DIPG is (more recently called DMG) to help raise awareness of this killer paediatric cancer.

What are brain tumours and how many types are there?

Every year in the UK, around 12,700 people are diagnosed with a primary brain or central nervous system tumour. There are around more than a hundred different types of brain tumours, and they are differentiated according to a classification developed by the World Health Organisation (WHO). The current classification was published in 2021, but it is continually updated.

What are low-grade and high-grade brain tumours?

WHO classifies brain tumors as either low-grade or high-grade, depending on their behavior. The more normal the cells, the lower the grade. Grades 1 and 2 are slow-growing and less likely to spread to other parts of the brain. These account for around 53% of brain tumor diagnoses each year. High grades (3 and 4) are aggressive and fast-growing, accounting for around 47% of cases.

Within that classification, the names for brain tumours are determined by their location in the brain and the names of the cells they grow in. If a specific genetic mutation is identified, these can further classify how a brain tumour may respond to treatment (where that’s known).

NHS information on the disease is here: https://www.nhs.uk/conditions/brain-tumours/

What is a DIPG?

A DIPG (diffuse intrinsic pontine glioma) is now called a diffuse midline glioma or DMG and it is a high-grade brain tumour.

To explain each of those terms, diffuse means that the tumour spreads so that cancer cells mix with healthy cells. Intrinsic simply means “in,” referring to the point or origin.

The tumour forms in the glial cells, so it is called a glioma. Glial cells are found throughout the brain. They make up the white matter that surrounds and supports the neurons, which are cells that carry messages in the brain.

Pontine refers to the part of the brain where the tumour develops: the pons or midline area. This part of the brainstem is responsible for relaying signals from the cerebrum to the cerebellum that help with vital functions like sleeping, breathing, bladder control, posture, hearing, facial and eye movements.

How prevalent are diffuse midline gliomas?

Brain tumours are rare*, but tumours affecting the brain or spinal cord are the second most common cancer in children, according to Cancer Research UK.

There are around 12,700 new cases of brain tumours diagnosed every year in the UK. Children diagnosed with a diffuse midline glioma make up between 20 to 30 of those cases.

How to spot a DIPG

When cells grow uncontrollably in an area of the brain, they form a mass that puts pressure on nerves in those areas. While symptoms can vary, this can affect any of the functions for which the nerves in that part of the brain are responsible.

Therefore, some of the most common symptoms a child with DMG/DIPG may experience include:

• problems with walking, coordination or balance
• weakness in the arms and legs
• difficulty controlling facial expressions or one side of the face appearing different from the other
• speech difficulties
• problems with swallowing and chewing
• double vision or difficulty controlling eye movement
• bladder problems

As the tumour grows, it may block drainage of the cerebrospinal fluid that surrounds and nourishes the brain. This can cause a build-up of fluid within the skull, known as hydrocephalus, and the pressure from this can cause:

• headaches (especially in the morning)
• nausea
• fatigue

But there may be other less common symptoms. You can use this symptom tracker, which has sections relevant to babies and children, if you are at all worried: https://bettersafethantumour.com/

Treatment of a DIPG or DMG

Following a brain tumour diagnosis, a patient’s Multi-Disciplinary Team will determine the best course of treatment for them. This may involve either surgery, radiotherapy and chemotherapy, or a combination of all three.

But tragically, in the case of DMG or DIPG, there are currently no effective treatments. That’s because the location of the tumour means surgery is not an option because removing it could also damage the parts of the brain that control vital functions like breathing.

Radiotherapy for DIPG

Chemotherapy has been shown to be ineffective and so radiotherapy is the current standard of treatment with the aim of shrinking the tumour.

Do steroids reduce or control the symptoms of a brain tumour?

Steroids may also be prescribed to reduce swelling in the brain caused by the tumour and/or the side effects of radiotherapy. Alternatively, a shunt may be fitted to drain the fluid.

This means there is a very slim chance (less than 2%) of a child living with the disease for five years or more. The Brain Tumour Charity has more information here.

What is radiotherapy?

Radiotherapy is, effectively, high dose x-rays which can slow tumour growth by depositing energy within the tumour, damaging the cells’ DNA. If those cells cannot repair the damage, the tumour cells die when they try to divide.

Radiotherapy needs to be accurately targeted at the tumour and to do this a specially moulded mask for the face and head is created. The patient then needs to keep very still or be anaesthetised. This can be challenging and frightening for young children so a play therapist may work with them to make this less daunting.

While this type of tumour may initially respond to radiotherapy, the treatment has its risks and side effects, and the tumour is likely to grow back. There’s more information on radiotherapy for treating children here.

Causes of DIPG/DMG

Scientists do not yet know what causes brain tumours. They are indiscriminate and can affect anyone at any age.