What Is Astrocytoma?

Overview

An astrocytoma is a type of tumour that develops in the brain or the spinal cord and can often be cancerous. Astrocytomas are the most common form of tumour in adults. In fact, according to Cancer Research UK, 34 out of 100 brain tumours in England were confirmed to be astrocytomas (between 2006 and 2010). This article will be exploring some potential causes, signs, and symptoms as well as treatment and management options for astrocytomas. 

Astrocytomas are tumours that originate in the astrocytes, cells that support the nerves in the brain. Astrocytomas can be benign and slow growing or they can be more aggressive. This is determined by the grade of the tumour. The World Health Organisation (WHO) has classified astrocytomas into 4 grades based on several factors. These factors include the abnormality and growth rate of the tumour cells. Grade 1 (such as pilocytic astrocytoma) is usually found in children and is benign (non-cancerous ). Grade 4 is the most malignant and aggressive form of astrocytoma. 

Causes of astrocytoma

The causes of astrocytomas have not been fully identified, but for now, it is thought that astrocytomas come sporadically. That means that they occur by chance. However, there seemto be some factors, environmental and genetic, that increase the possibility of developing astrocytoma. 

Environmental: 

Studies have found that exposure to ionising radiation is linked to developing astrocytoma later in life, even 20 - 30 years later.¹ You are at a higher risk of astrocytoma if you have been exposed to therapeutic ionising radiation (especially in areas around the head and neck) to treat other brain tumours or leukaemia at an early age. For years, it was suspected that increased exposure to mobile phones might be associated as well, however, no findings support such a claim.  

Genetic: Some hereditary mutations have also been linked to astrocytoma formations. These include: 

• Li-fraumeni Syndrome - Disorder in which the individual is missing the p53 gene which is linked to tumour suppression. As a result, the person can suffer from several types of tumours, breast cancer, bone cancer and astrocytoma.
• Turcot - Disorder that is characterised by colon cancer and astrocytomas, due to mutations in tumour suppressor genes. 
• Neurofibromatosis type 1 - Disorder that is characterised by astrocytomas and peripheral nerve tumours as well as skin freckling and brown skin patches, due to a mutation in the NF1 tumour suppressor gene.
• Tuberous Sclerosis - Rare genetic condition that causes benign (non-cancerous) tumours to develop in different parts of the body. 

Signs and symptoms of astrocytoma

Symptoms of astrocytoma are heavily reliant on the location of the tumour. Certain regions of the brain, such as the area behind the forehead, have a much larger capacity to “accommodate accomodate” or fit larger tumours before the patient presents with symptoms. However, other regions are a lot more sensitive and even a small tumour can make the patient symptomatic early on. Naturally, higher-grade astrocytomas are more aggressive and cause more severe symptoms faster, compared to lower-grade astrocytomas. This happens because low-grade astrocytomas usually displace the brain and high-grade astrocytomas cause inflammation and destroy it. Symptoms also often occur from the pressure caused by the tumour. This pressure prevents certain areas of the brain from working properly. 

Common symptoms you can look out for include; 

1. Prolonged headaches or headaches that are worse when you wake up/ cause you to wake up during the night 
2. Blurred or double vision
3. Speech impairments (such as slurring) 
4. Cognitive disabilities (such as problems with memory)
5. Weak limbs or weak grasp 
6. Occurrence of seizures 
7. Nausea and/ or vomiting 
8. Trouble with coordination or balance 
9. Sudden mood changes  

It is worth noting that these symptoms are not exclusive to astrocytomas, or tumours in general. However, if you are experiencing these symptoms and you suspect a tumour, contact your doctor.  

Management and treatment for astrocytoma

In most cases, the optimal option for astrocytoma treatment is surgery, to remove the tumour.² However, the possibility of surgery depends on the location of the tumour. The goal of the surgery is to safely remove as much of the tumour as possible, without impairing other brain areas or functions. Removing part of the tumour, or the whole tumour can help reduce swelling and increase the response to adjuvant therapies. Adjuvant therapies will be discussed below. As already mentioned, depending on the location, the surgeon will decide if the tumour can be removed or if they can only perform a biopsy in order to diagnose the tumour. It is worth mentioning that the extent of resection is associated with higher overall survival. This means that studies have found that when a larger part of the tumour was removed during surgery, the better the survival rate of the patient will be.³

Adjuvant therapies are secondary therapy options administered after the primary treatment - in this case, surgery - in order to ensure that the tumour will not return. When it comes to astrocytomas, adjuvant therapy options include chemotherapy, radiotherapy, steroids and anti-seizure medication. 

Chemotherapy uses oral administration of a drug called temozolomide (TMZ) to try and alter the DNA of the tumour cells. TMZ is a well-established therapy and is used often for astrocytomas that are higher grade. TMZ can also be used for 2nd grade astrocytomas that were not fully removed during surgery. TMZ is taken for 5 days, followed by a 3 week “rest” period. After this period you start another cycle. Side effects include fatigue and anaemia. 

Radiotherapy is used in the first few months after surgical treatment. Radiotherapy is thought to damage the tumour cells’ DNA. Radiation is administered in small doses, 5 days a week for 6 weeks. However, radiotherapy has several side effects, such as hair loss and fatigue. Long term, it can cause cognitive deficits. 

​​Steroids are used to reduce inflammation in the brain that is often caused by tumours. While steroids do not actually treat the tumour, they are effective in terms of alleviating symptoms caused by the swelling. Unfortunately, steroids have a lot of side effects, such as weight gain, increased chance of infection, irritability and high blood sugar levels. 

Anti-seizure medications are administered to patients that experience seizures.

FAQs

How is astrocytoma diagnosed?

The diagnosis of astrocytoma includes several tests. Firstly, you are required to have a neurological exam. During this exam, you will be asked to describe your symptoms and concerns. Then, your doctor will assess your vision, balance, hearing, and reflexes. If you present with abnormalities or problems in any of these areas, this may indicate that your brain or spinal cord is affected by a tumour. 

After assessing the neurological exam, your doctor will decide whether additional testing is required. The first imaging test you will probably have to do is an MRI scan. MRI scans are used to diagnose and locate the tumour. In some cases, specialised MRIs such as functional MRI or perfusion MRI are recommended. Functional MRI can show in real time which areas of your brain are activated when performing certain tasks. As a rule of thumb, if the tumour is brighter on the MRI images, chances are the tumour is of a higher grade. Other imaging tests you might need to do are CT scans and PET scans. All these tests can help diagnose the size and location of the tumour. 

While these tests are very helpful they cannot always diagnose the exact type of tumour. Therefore you may require a biopsy. A biopsy happens before or during surgery with a needle. The option to have surgery heavily depends on the location of your tumour. A sample of the tumour is removed and analysed in the lab. This allows doctors to determine the type of tumour and how aggressive it is. Biopsies are very important and can help your doctor determine your prognosis and decide the best treatment option for you. 

Can astrocytomas be prevented?

While the exact causes of astrocytomas have not been identified, it is always worth trying to protect yourself. Avoiding hazardous behaviours such as smoking and radiation exposure is important.

Who are at risk of astrocytoma?

Anyone can develop astrocytomas, however, smokers and people that have been exposed to radiation are at higher risk. Several genetic diseases mentioned in the “Causes of astrocytoma” section are also associated with a higher risk. 

Children are usually affected by Grade 1 astrocytomas whic h are most often benign. The rest of the 3 grades are found in adults usually over the age of 40. 

How common is astrocytoma?

Astrocytomas are the most common form of tumour in adults. In fact, according to Cancer Research UK, 34 out of 100 brain tumours in England were confirmed to be astrocytomas (between 2006 and 2010). 

When should I see a doctor

If you are experiencing: 

• Prolonged headaches or headaches that are worse when you wake up/ cause you to wake up during the night 
• Blurred or double vision
• Speech impairments (such as slurring) 
• Confusion or cognitive impairments 
• Seizures
• Weakness in limbs 
• Nausea/ vomiting 

While these symptoms do not necessarily indicate that you have a brain tumour, it is always the safest option to contact a doctor about them. 

Summary

Overall, astrocytomas are tumours that emerge from astrocytes and affect the brain or the spinal cord. Causes are not yet fully established, however, exposure to ionising radiation and several genetic diseases seem to be linked to a higher risk of developing astrocytoma. Astrocytomas can range from grade 1 (non-cancerous , slowly growing) to grade 4 (most malignant, fast-growing ). Symptoms are determined by the location of the tumour and can include prolonged headaches, vision, speech and cognitive difficulties as well as nausea and vomiting. In most cases, surgery is the optimal treatment option and depending on the individual patient, continuing treatment with chemotherapy or radiotherapy is recommended.