Astrocytoma is a type of tumor that grows in the patient’s brain or spinal cord. It develops from a type of cells called astrocytes, which are responsible for connecting and supporting the nerve cells located in the spinal cord and brain.
Astrocytoma by itself is a very rare disease, however, it is one of the most common types of brain tumors. This disease can affect both children and adults, and usually lower grade astrocytomas affect children and teens, while higher grade astrocytomas affect adults and senior citizens.
To properly understand astrocytoma, we need dive deep into its grading, causes and symptoms.
Since astrocytoma is a type of tumor, its progression is measured in grades. There are 4 grades of astrocytoma, and the higher the grade, the more serious the condition.
Astrocytoma Grade 1
Grade 1 astrocytoma is the mildest form, and these tumors are benign, meaning they aren’t cancerous. There are three different types of grade 1 astrocytoma:
- Pilocytic astrocytoma
- Pleomorphic xanthoastrocytoma
- Subependymal giant cell astrocytoma (SEGA)
All of these tumors are the least aggressive and very slow-growing, but in some rare cases, they may exhibit some more aggressive behavior. They’re typically found in children and young adults and have an excellent prognosis.
Astrocytoma Grade 2 (Diffuse Astrocytoma)
Grade 2 astrocytoma, which is also referred to as diffuse astrocytoma, is defined by a slower growth rate and moderately abnormal cells. However, they do grow quicker than grade 1 tumors and can grow into a higher grade. This is a malignant and invasive tumor and is often found in adults between the ages of 20 and 40.
Astrocytoma Grade 3 (Anaplastic Astrocytoma)
Astrocytoma, or anaplastic astrocytoma, is a high-grade and aggressive malignant tumor. It is defined by highly abnormal cells that grow rapidly and don’t have the function or structure normal cells do nor are they uniform in appearance. They’re most often found in adults between the ages of 30 and 50,
Astrocytoma Grade 4 (Glioblastoma)
Glioblastoma, or grade 4 astrocytoma, is the most severe form of this tumor. It is often composed of several different types of cells, all of which are abnormal, and it invades the brain tissue near the tumor.
Astrocytoma can grow into grade 4 from a lower grade, or it can develop into grade 4 as soon as it manifests itself. Glioblastoma can appear in people of all ages, but it is most common in patients over the age of 60.
Astrocytoma Biological Features
Understanding astrocytoma also entrails understanding all of its biological features. There are three main biological changes that occur in patients suffering from this tumor:
- IDH1 mutation. Isocitrate dehydrogenase 1, also simply known as IDH1, is a gene that provides energy to a person’s cells and creates the enzyme isocitrate dehydrogenase 1. When it mutates, it creates a chemical called 2-HG that builds up inside normal astrocytes. Over time, this chemical causes the astrocytes to change their biological structure and turn into astrocytomas. Almost all low-grade astrocytomas have this mutation.
- MGMT silencing. MGMT, or methylguanine-DNA methyltransferase, is an enzyme that is responsible for repairing the DNA of patients who have gone through chemotherapy. This in turn protects the tumor against these drugs. Some forms of astrocytoma have this enzyme turned off, and this has a positive effect on treatment response and leads to a more favorable prognosis.
- Immunologic escape. This biological feature refers to the ability of pathogens to either evade or suppress the defense mechanisms of the host’s immune systems. Astrocytoma is in a group of tumors that has a highly developed immune escape and can therefore escape the immune system’s natural surveillance.
Astrocytoma Causes and Risk Factors
To this day, medical professionals aren’t sure what exactly causes astrocytoma as most cases seem to appear sporadically and without any explanation. While it is known that brain tumors are caused by rapidly dividing brain cells, what leads to this is, for the most part, unknown.
That being said, there are certain risk factors that are associated with a higher chance of developing astrocytoma.
The biggest risk factors are associated with certain genetic disorders, which are usually passed onto children from parents. These disorders include:
- Li-Fraumeni syndrome. A rare genetic disorder that is caused by a suppressor gene, more specifically the TP53 tumor suppressor gene. This gene is responsible for regulating cell growth and preventing tumors from being formed. If this gene mutates, it leads to Li-Fraumeni syndrome, which increases the host’s risk of developing a tumor such as astrocytoma.
- Neurofibromatosis type-1. A mutation in the NF1 gene, which is responsible for creating a protein by the name of neurofibromin, which is another type of tumor suppressor, leads to neurofibromatosis type-1. Patients who have this genetic disorder are more susceptible to developing astrocytoma as their cell growth and division aren’t well-regulated.
- Tuberous sclerosis. This genetic disorder is caused by mutations in the TSC1 or TSC2 genes and patients who suffer from this disorder have a much higher chance of developing benign tumors in all parts of the body, including the brain.
- Turcot syndrome. This specific syndrome is linked to certain gene mutations, such as mutations of the APC gene or mismatch repair genres. The mutations that occur due to Turcot syndrome are frequently linked to the development of brain tumors and other types of cancer.
Astrocytoma Symptoms Symptoms
However, there are some symptoms most astrocytoma patients experience:
Some of the most common signs and symptoms of pediatric astrocytomas include:
- Persistent headaches that often worsen over time.
- Memory problems and cognitive changes, such as finding it difficult to concentrate.
- Difficulty with coordination and balance.
- Slurred speech and overall speech problems.
- Fatigue and weakness.
- Blurred vision or double vision.
- Limb weakness.
If a doctor suspects the presence of astrocytoma or any other tumor, they will perform a variety of tests to determine what condition the patient is suffering from.
These tests include:
- A physical exam and health history. The first test for diagnosing an illness is a physical exam and a health history overview. This is when the doctors look for physical signs of an illness and see whether there are any health history concerns that would indicate the patient has an increased risk factor for developing astrocytoma.
- Neurological exam. To check for astrocytoma, the doctor will have to perform a neurological exam which will check the patient’s brain, spinal cord, and nerve function.
- Visual field exam. As blurred vision is one of the side effects of astrocytoma, if the doctor suspects the patient has this tumor, they will order a visual field exam. This exam will determine how much vision the patient has in each eye and if they have any blind spots.
- Magnetic resonance imaging (MRI) with gadolinium. An MRI will allow the doctor to see all of the abnormal physical changes in the brain if there are any. The patient will also receive gadolinium before their MRI, which is a special dye that will make the results easier to read.
- CT scan. If the doctor in charge of the case needs a more precise and clear image than the one produced by the MRI machine, they will order a CT scan. This machine uses multiple X-rays to take pictures of the entire body from multiple angles so they can produce highly detailed images.
- Biopsy. When the doctor determines the presence of astrocytoma, they also need to find what exact subtype the patient is suffering from, and that can be done with a biopsy. During a biopsy, a medical professional will remove a piece of tissue from the tumor and examine it under a microscope. This will help them figure out the grade and the type of tumor.
- Lumbar puncture. To see whether the astrocytoma is located in the spinal cord, the doctor will order a lumbar puncture to see if there are any cancerous cells in this area of the body.
- Molecular testing. Another way to determine the specific subtype of astrocytoma the patient is suffering from is through molecular testing. Certain types of astrocytoma come with specific genes and proteins, and molecular tests can see whether they’re present or not.
After making an astrocytoma diagnosis, the doctor in charge of the case will be able to determine the best possible treatment. These are all the treatment options available:
Observation and close monitoring. For stage 1 astrocytoma, no special treatment is required as the tumor is benign. All that’s needed is close observation and monitoring to see if the tumor grows or progresses to a more advanced stage.
Surgery. The first treatment option for all malignant and some benign tumors is surgery, during which a surgeon removes the entire or at least part of the tumor.
Chemotherapy. After surgery, the patient will receive rounds of chemotherapy in hopes of achieving remission.
Bone marrow transplant with high-dose chemotherapy. Since high-dose chemotherapy often damages bone marrow, doctors will often perform a bone marrow transplant to allow the patient’s blood cells to better fight off the disease.
Radiotherapy. In some more extreme cases when chemotherapy is not enough, usually for stage 3 and 4 astrocytoma, the patient will have rounds of radiotherapy along with chemotherapy.
Targeted therapy. If the doctor is looking to treat the patient without destroying any healthy cells, they may administer targeted therapy. This treatment option can block the tumor cell from spreading and only target the specific area that’s causing issues and stop the cancerous cells from growing or developing any further.
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