Astrocytomas are a common type of glioma, which develop from the glial (or supportive) cellsthe basic structural and functional unit of all living things in the central nervous system (CNS). More specifically, they develop from a type of glial cell called astrocytes, a star-shaped cell that has a variety of functions, including regulating bloodthe red bodily fluid that transports oxygen and other nutrients around the body flow and regulating and maintaining synapses. Astrocytomas can develop in any area in the CNS, including the brain and spinal cord.
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 regulates many vital bodily processes, such as swallowing, breathing, and heart rate. 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 tissuea group of cells that work together to perform a function, 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).
Astrocytomas are more common in children between the ages of five and eight, and tend to affect the sexes equally. However, anyone can develop this disease.
Types of Astrocytomas
There are several different types of astrocytomas, which are categorised by how the cells look under the microscope.
Pilocytic Astrocytoma
Pilocytic astrocytoma, also known as juvenile astrocytoma, is a slow growing subtype of astrocytoma that primarily affects children. It is classified as a gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells I tumoura tissue mass that forms from groups of unhealthy cells, and develops slowly over time. Pilocytic astrocytomas are often found in the cerebrum, cerebellum, optic nerve pathway, or the brain stem. It is generally non-aggressive, and often has a good prognosisto predict how a disease/condition may progress and what the outcome might be.
Subependymal Giant Cell Astrocytoma
Subependymal giant cell astrocytomas (SEGAs), also known as intraventricular astrocytomas, are very rare and slow growing subtypes of astrocytomas that primarily affect children and adolescents. They are generally classified as grade I tumours, and often develop in the ventricles of the brain, which are responsible for the production and secretion of cerebral spinal fluid (CSF). While SEGAs are generally not aggressive, they may not have as good of a prognosis as other types of astrocytomas due to the potential obstruction of CSF flow.
Desmoplastic Infantile Astrocytoma (DIA)
Desmoplastic infantile astrocytoma (DIA) is a very rare form of astrocytoma that is generally diagnosed in children under two years old. It is generally classified as a grade I tumour, and is often found in the cerebrum. DIAs are usually slow growing, and can have a good diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results when found early.
Diffuse Astrocytoma
Diffuse astrocytoma is a slow growing subtype of astrocytoma that generally affects young adults. This type of cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs is generally classified as a grade II tumour, is widespread, and has poorly defined borders (diffuse). Diffuse astrocytomas are generally found in the cerebrum, and often grow into nearby structures in the brain. This type of tumour can be non-aggressive, and can have a good prognosis when found early.
Pleomorphic Xanthoastrocytoma
Pleomorphicmany forms; cells that have different size, shape etc. Xanthoastrocytoma (PXA) is a very rare subtype of astrocytoma that generally affects children and adolescents. Unlike most types of astrocytoma’s, PXA does not affect the sexes equally, and has a prevalence for males. It is generally classified as a grade II tumour, and are often found in the cerebellum. PXAs are usually slow growing, and can have a good prognosis.
Anaplastic Astrocytoma
Anaplastica term used to describe abnormal cancer cells that grow uncontrollably in the body and have little or no resemblence to regular cells astrocytoma is a rare subtype of astrocytoma that generally affects adults between the ages of 30 and 50. These cancers are generally classified as grade III tumours, and are often found in the cerebrum. Anaplastic astrocytoma’s are generally aggressive, often metastasise, and may not have as good of a prognosis as other types of astrocytoma.
Anaplastic Pleomorphic Xanthoastrocytoma
Anaplastic pleomorphic xanthoastrocytomas (APXAs) are a very rare subtype of astrocytoma that generally affect young adults. Unlike most types of astrocytoma’s, APXA does not affect the sexes equally, and has a prevalence for males. It is generally classified as a grade III tumour, and is often found in the cerebrum. APXA are generally aggressive, and may not have as good of a prognosis as other astrocytomas.
Glioblastoma
Glioblastomas, also known as glioblastoma multiforme (GBM), are a common type of brain tumour that generally affects adults between the ages of 50 and 80. Unlike most types of astrocytomas, GBM does not affect the sexes equally, and has a prevalence for males. Its name is derived from its cellular appearance under the microscope, which is often highly varied. GBM is generally classified as a grade IV brain tumour, and is usually found in the cerebrum. For more information on glioblastomas, please refer to the Rare Cancers Australia Glioblastoma page.
Diffuse Midline Glioma
Diffuse midline gliomas (DMGs) are a rare type of astrocytoma that generally affects children. These tumours often form in the midline structures of the brain, such as the pons in the brainstem, thalamus, spinal cord, and cerebellum. For more information on DMGs, please refer to the Rare Cancers Australia Diffuse Midline Glioma page.
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 cells 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.
Astrocytomas are generally graded by subtype:
- Grade I (low grade) tumours: cancer cells present as slightly abnormal and are usually slow growing. Includes pilocytic astrocytomas, subependymal giant cell astrocytomas, and DIAs.
- Grade II (intermediate grade) tumours: cancer cells present as abnormal and grow faster than grade-I tumours. Includes diffuse astrocytomas and pleomorphic xanthoastrocytomas.
- Grade III (high grade) tumours: cancer cells present as very abnormal and grow quickly. Includes anaplastic astrocytomas and anaplastic pleomorphic xanthoastrocytomas.
- Grade IV (high grade) tumour: cancer cells present as very abnormal and grow very quickly. Grade IV tumours are more aggressive than grade III tumours. Includes glioblastoma and diffuse midline glioma.
Once your tumour has been graded, your doctor may 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, stage of disease and overall health.
Treatment options for astrocytomas may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence to remove the tumour.
- Watch and waitthe close monitoring of a cancer without giving treatment until symptoms appear or worsen.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Stem cell transplanta procedure that involves replacing unhealthy blood-forming cells (stem cells) with healthy stem cells.
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Immunotherapya treatment that uses a person's immune system to fight cancer.
- 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.
Risk factors
Although it is a relatively common type of brain tumour, it is not clear what the riskthe possibility that something bad will happen factors for astrocytomas are. However, researchers have identified a potential link to certain genetic changes in DNA.
Symptoms
Astrocytomas may appear asymptomatic in the early stages of disease. As the cancer progresses, some of the following symptoms may appear:
- Headaches (commonly in the morning, and may go away after vomiting).
- Nauseato feel sick or likely to vomit and/or vomiting.
- Difficulties with vision, hearing, and/or speaking.
- Loss of balance.
- Difficulties walking.
- Syncopefainting or passing out.
- Worsening handwriting and speaking skills.
- Weakness or changes in one side of the body.
- Fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
- Changes in energy levels.
- Changes in personality and behaviour.
- Seizures.
- Unexplained weight loss or weight gain.
- Unusual increase in head size (in infants).
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 Childhood Glioma (including Astrocytoma) page published by the National Cancer Institute.
Diagnosis
If your doctor suspects you have an astrocytoma, 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:
- 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 (most common).
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- PET (positron emission tomography) scana type of medical imaging that uses radioactive tracers to create detailed images of the body.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
