Diffuse intrinsic pontine glioma (DIPG) is a rare and highly aggressive cancer that develops from glial (or supportive) tissue in the brain, which supports and protects the brains neurons. More specifically, it develops in an area of the brainstem called the pons, which is found at the base of the brain.
The brainstem is a thin, stalk-like structure that connects the brain and the spinal cord. It is divided into three sections: the midbrain (or mesencephalon), pons (or metencephalon), and medulla (or medulla oblongata). Each component of the brainstem works together to control and regulate vital bodily functions, such as breathing, heart rate, blood pressure, as well as the nerves and muscles used for seeing, hearing, walking, talking, and eating. As DIPG grows in the pons, the tumour puts pressure on the nerves and adjacent structures in the brain, which causes adverse changes in these bodily functions.
DIPGs and diffuse midline gliomas (DMGs) are often classified together, but can have different treatment options. For more information on DMGs, please refer to the Rare Cancers Australia Diffuse Midline Glioma page.
DIPG is almost exclusively diagnosed in children, most commonly between the ages of four and eleven. However, anyone can develop this disease.
Treatment
When cancers are detected, they are staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body), and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, brain cancers are rarely staged, as they rarely spread to other parts of the body. Instead, they are generally graded.
Because of the location in which DIPG develops, how aggressive they are, and how rapidly they progress, DIPG is considered a ‘high grade’ tumour. High grade tumours are defined by cancer cells that look very different from normal surrounding cells and by rapid tumour progression.
Your doctor may also recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Unfortunately, there are limited, effective treatment options for DIPG. Surgery is not generally an option for patients with DIPG, because the tumour is not-well contained (of diffuse) and because of its location. Attempting to surgically remove a DIPG tumour would most likely result in neurological damage, and can be fatal.
Treatment options for DIPG may include:
- Palliative radiation.
- Experimental chemotherapy.
- Steroids.
- Insertion of a stent to relieve build-up of cerebrospinal fluid (CSF) in the brain.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Clinical Trials for DIPG
Clinical trials are research studies performed to test new treatments. They present the opportunity for people, particularly those with rare or complex cancers such as DIPG, to receive very new treatments which are not yet available otherwise. While these studies have the potential to develop more treatment options, the risk of side effects can be high and are not always known.
Ask your doctors about the availability of clinical trials and whether your child is suitable, as well as any benefits, risks and potential complications that may arise.
Risk Factors
Because of how rare DIPG is, there has been limited research done into the risk factors of this disease. However, some recent research has suggested that there is a potential link to abnormal brain development and certain genetic and epigenetic mutations.
Early Symptoms
In most cases, the onset of symptoms occurs very rapidly before diagnosis, reflecting the fast growth of DIPG tumours. Because of the aggressive nature of these tumours and their growth rate, symptoms generally progress very quickly.
Common symptoms of DIPG include:
- Problems controlling eye movement, facial expressions, chewing and/or swallowing (as a result of nerve compression in the brain).
- Slurred speech.
- Difficulties with balance.
- Hydrocephalus (fluid build-up in the brain).
- Headaches (often after waking up in the morning).
- Nausea and/or vomiting (generally worse in the morning).
- Irritability.
- Blurred or double vision.
- Seizures.
- Lethargy (lack of energy).
- Fatigue.
- Changes in eating habits/appetite.
- Difficulty walking.
- Personality changes.
- Enlarged fontanelles (soft spots on an infant's head between the bony plates of the skull).
- Enlarged head (more common in infants).
- Facial drooping.
- Difficulties urinating.
- Weakness in the arms and/or the legs.
- Clumsiness.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a DIPG, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.
Imaging & Blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-rays and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and look for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Neurological examination
A neurological examination assesses sensory and motor functions, and can generally be done in your GPs office. The doctor may check your vision, hearing, balance, coordination, strength, and reflexes, depending on the signs and symptoms you have described. Any problem that is detected in this exam can help determine which portion of the CNS needs further investigation.
Biopsy
Once the location of the cancer has been identified, the doctor may perform a biopsy to remove a section of tissue using a needle. This sample will then be sent to the lab and analysed for cancer cells.
Because of the tumour location and its diffuse nature, biopsies are not always performed in patients who are suspected to have a DIPG. In many cases, a diagnosis can be given based on other tests.
Prognosis
Unfortunately, the prognosis for DIPG remains very poor. Brain tumours remain the most common cause of cancer-related death in children, and DIPG is the leading cause of death from paediatric brain tumours.
A child diagnosed with DIPG today faces the same prognosis as a child diagnosed 40 years ago. There is still no effective treatment and no chance of survival. Only 10 per cent of children with DIPG survive for two years following their diagnosis, and less than one per cent survive for five years. The median survival time is nine months from diagnosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.