Diffuse midline gliomas (DMG) are a rare and aggressive type of cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs that develops from glial (or supportive) tissuea group of cells that work together to perform a function in the brain, which supports and protects the brains neurons. They develop within the midline structures of the body, including the brainstem, spinal cord, and thalamus, and most commonly affect children.
The brain is a complex organ that is responsible for controlling all functions of the body. It has five main portions: the cerebrum, cerebellum, brainstem, pituitary gland, and hypothalamus. The cerebrum is the biggest part of the brain, and consists of the frontal, parietal, temporal, and occipital lobes. This part of the brain is responsible for voluntary movement, intelligence, and memory. The cerebellum is a small part of the brain located at the back of the head, and regulates posture and balance. The brainstem is a small, stalk-like structure towards the bottom of the brain that connects the brain to 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, bloodthe red bodily fluid that transports oxygen and other nutrients around the body pressure, as well as the nerves and muscles used for seeing, hearing, walking, talking, and eating. The pituitary gland is a pea sized organ located behind the eyes, and is responsible for the production and secretion of hormones in the body. The hypothalamus is located deep within the brain, and has many important functions, such as producing and secreting different hormones, regulating temperature, and controlling appetite.
The spinal cord is a long, thin, tubular structure that extends down from the brainstem to the lower back. It is made of nerve tissue, and is surrounded by the bones of the spine (vertebrae). The spinal cord is responsible for transmitting nerve signals from the brain to the body, and vice versa. It has motor functions (such as voluntary movement), sensory functions (such as pressure, touch, temperature, and pain), and autonomous functions (such as regulating digestion, heart rate, and blood pressure).
DMGs and diffuse intrinsic pontine gliomas (DIPGs) are often classified together, but can have different treatment options. For more information on DIPG, please refer to the Rare Cancers Australia Diffuse Intrinsic Pontine Glioma (DIPG) page.
DMGs are slightly more common in males, and are most commonly diagnosed between the ages of five and seven. However, anyone can develop this disease.
Treatment
When cancers are detected, they are staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cellsthe basic structural and functional unit of all living things look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas 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 from I-IV.
DMGs are considered to be gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells IV tumours, as the tumoura tissue mass that forms from groups of unhealthy cells cells appear very abnormal under the microscope and grow rapidly.
Your doctor may also recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, 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.
Treatment is dependent on several factors, including location, age, and overall health.
Treatment options form DMG may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence to remove as much of the tumour as possible (if possible – dependent on tumour location).
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Experimental chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Corticosteroidsa type of anti-inflammatory medication that is used to treat inflammation.
- Shunt insertiona procedure to relieve build-up of cerebrospinal fluid (CSF) in the brain.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Some of the information regarding treatment was obtained from the Diffuse Midline Glioma: Diagnosis and Treatment page published by the National Cancer Institute.
Clinical Trials for DMG
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 DMG, to receive very new treatments which are not yet available otherwise. While these studies have the potential to develop more treatment options, the riskthe possibility that something bad will happen 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 DMG 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.
Symptoms
In most cases, the onset of symptoms occurs very rapidly before diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results, reflecting the fast growth of DMG tumours. Because of the aggressive nature of these tumours and their growth rate, symptoms generally progress very quickly.
Common symptoms of DMG 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.
- Hydrocephalusa build up of cerebrospinal fluid (CSF) in the brain, causing pressure and potentially damaging brain tissue.
- Headaches (often after waking up in the morning).
- Nauseato feel sick or likely to vomit and/or vomiting (generally worse in the morning).
- Irritability.
- Blurred or double vision.
- Seizures.
- Lethargylack of energy, fatigue.
- Fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
- 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 and/or with bowelportion of the digestive system that digests food (small bowel) and absorbs salts and water (large bowel); also called intestines movements.
- Weakness and/or numbness 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.
Some of the information regarding symptoms was obtained from the Diffuse Midline Glioma: Diagnosis and Treatment page published by the National Cancer Institute.
Diagnosis
If your doctor suspects you have a DMG, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Neurological examinationan assessment of sensory and motor functions, such as vision, balance and coordination.
- Imagingtests that create detailed images of areas inside the body tests, potentially including a MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
Biopsy
Because of the tumour location and its diffuse nature, biopsies are not always performed in patients who are suspected to have a DMG. In many cases, a diagnosis can be given based on other tests.