What Is Medulloblastoma?

Introduction

Medulloblastoma is a type of brain cancer that accounts for approximately 15-20% of all brain cancers found in children, making it the second most common childhood brain cancer in the UK. Each year, around 52 young people between the age of 3-8 are diagnosed with childhood medulloblastoma in the UK. Medulloblastoma occurs more commonly in children assigned male at birth than in children assigned female at birth.

The occurrence of medulloblastoma decreases when a child grows with age, making adult medulloblastoma rare.^1,2

In this article, we will continue reading to learn more about medulloblastoma, including what causes it, how it manifests in patients, and its current treatments. 

Overview

The human brain is a complex structure that controls various actions such as memory, movement, breathing, heart rate, vision and overall body maintenance.

The cerebellum is a region of the brain at the base of the skull and is in charge of coordinating movements and maintaining balance. Medulloblastoma is prone to appear in this preferred region. 

It spreads into the cerebellum and invades as a malignant tumour the entire central nervous system.^2,3

 Medulloblastoma is an embryonic tumour, it originates from early developmental cells ( foetal cells that remain after birth) in the brain. As a result, this type of brain cancer is more prevalent in children compared to adults. At the time of diagnosis, approximately 30% of children with advanced medulloblastoma tumours. In recent years, advancements in research have led to the identification of new types and subtypes of medulloblastoma. This has been made possible by the discovery of specific genetic and molecular information related to this type of brain cancer.³

The four main types of medulloblastoma that occur are classified based on the genetic changes within the tumour cells are:^1,3,4

1. WNT-activated medulloblastoma (subtype-1): This subtype of medulloblastoma is less aggressive and has a  >90% of survival.  The genetic is influenced by the wingless-related intergration site (WNT) signalling pathway;  it functions as a messenger between cells, communicating commands to either continue growing and dividing or to cease

The brain’s tissue depends on  the WNT signalling for growth and maintenance . Disruption of this pathway leads to uncontrolled cell division and tumour formation.  

2. SHH-activated medulloblastoma (subtype-2): Another subtype more common in infants and young children. The sonic hedgehog signalling (SHH) works like a switch, turning on or off specific genes that are important to cell growth and differentiation

When this signalling pathway is disrupted by specific genetic changes, it can lead to abnormal cell growth and division, causing the formation of tumours. 

3. Group 3 medulloblastoma (subtype-3): The subtype of medulloblastoma is more aggressive and has a lower rate of survival. It is characterised by genetic changes that affect the expression of genes involved in cell growth and differentiation

4. Group 4 medulloblastoma (subtype-4): This type of medulloblastoma is the most common and has an intermediate prognosis. It is characterised by a lack of specific genetic changes and is often diagnosed in older children

Understanding the different subtypes of medulloblastoma is crucial for doctors to tailor treatment plans for each patient. By identifying specific genetic and molecular information of each subtype, doctors can better understand how aggressive the tumour is and how it might respond to the treatments.

Researchers actively monitor these subtypes to improve treatment options and develop new therapies targeting each subtype. These efforts will provide a  better outcome for patients with medulloblastoma and reduce the potential side effects of treatments.

What causes medulloblastoma?

The exact origin of medulloblastoma is still unknown, but research has indicated that the environmental and genetic factors involved may change. 

Genetic changes can occur spontaneously. Although, it can inherit the known risk factors for the development of childhood medulloblastoma. 

Medulloblastoma developed in older patients is not yet well understood. The ongoing studies hope to unravel the cause.³

The associated risk factors with the cause of medulloblastoma are:^1,3.5

• Genetic mutations: Some genetic mutations identified contribute to the development of medulloblastoma. These mutations may occur spontaneously or  from parental inheritance. For example, mutations in the P53: gene, and variants of BRCA1 and BRCA2 associate  with an increased risk of developing medulloblastoma
• Nevoid basal cell carcinoma syndrome (NBCCS): The NBCCS also known as  Gorlin-Goltz syndrome is a hereditary disorder that results in a number of basal cell skin cancers that manifest as cysts.
•  The syndrome shows 5% risk of getting medulloblastoma
• Turcot syndrome: Turcot is an infrequent genetic disease and a type of hereditary condition: familial adenomatous polyposis (FAP). FAP results in  gene mutations that increase the risk of both colorectal (colon) cancer and central nervous system tumours: medulloblastoma or pituitary adenoma

Individuals with Turcot syndrome have about a 3-8% chance of developing medulloblastoma.

• Radiation exposure: Exposure to ionising radiation, particularly at a young age, has been identified as a risk factor for developing medulloblastoma. Likewise, exposure from radiation therapy  and other conditions  like environmental sources, such as nuclear accidents

There is a possibility that the gene is inherited, and early genetic testing might be the best precautionary measure. Talking with your GP will help you understand the risks involved and the best preventive approaches. The causes of medulloblastoma are likely multifactorial, involving a combination of genetic and environmental factors.

What are signs and symptoms of medulloblastoma?

The symptoms of medulloblastoma can differ depending on a few factors; age, tumour size, and stage of development. The symptoms may occur due to the preference of the tumour’s location or pressure built up inside the malignant brain tumour.

 Here are signs and symptoms of medulloblastoma to look out for:^1,3,6

• Headaches: A persistent headache that does not respond to paracetamol is a common symptom of medulloblastoma. The headache may be worse in the morning or when lying down
• Nausea and vomiting: Medulloblastoma causes nausea to vomit, particularly in the morning or after eating
• Loss of balance and coordination: Medulloblastoma can affect the cerebellum, which is responsible for balance and coordination.  The symptoms produce unsteadiness, clumsiness, and difficulty with fine motor skills
• Dizziness: Medulloblastoma can cause  lightheadedness   or dizziness, particularly when standing up or moving quickly
• Vision problems: Medulloblastoma can cause vision problems, such as blurred vision, double vision, or loss of peripheral vision if the tumour spreads to the optic nerve
• Changes in behaviour or personality: Medulloblastoma can affect the mood, behaviour, and personality. This can include irritability, depression, or a change in loss of peripheral vision in social behaviour
• Seizures: Seizures are common symptoms in childhood medulloblastoma as the cellular communication gets affected by the brain tumour
• Hearing problems: Medulloblastoma can cause hearing problems, such as hearing  ringing  or hearing loss
• Increased intracranial pressure: As the tumour grows, it can increase pressure within the skull and symptoms such as lethargy, confusion, and coma do appear

  Other medical conditions can trigger these symptoms. Hence, to produce an accurate diagnosis and treatment can be solved by visiting a GP. It is important to note that some patients may not experience the symptoms until the tumour is large. If you or your child experiences any symptoms, it is necessary to seek medical attention.

What are the management and treatment for medulloblastoma?

Medulloblastoma treatment comes with combinations of surgery, radiation therapy, and chemotherapy. The specific treatment plan depends on factors such as the patient's age, the size and location of the tumour, and the subtype of medulloblastoma.

The current treatment strategies used are:^3,5,6

• Surgery: Surgery is often the first treatment of choice. The surgery’s goal (surgical resection/craniotomy) is to retrieve the tumour as possible without damaging surrounding brain tissue. If the tumour’s location is too difficult to access, the surgeon may use a minimally invasive technique such as endoscopy
• Radiation therapy: After the surgery, radiation therapy targets to kill any remaining cancerous cells and prevent the tumour from growing back.  The procedure uses external beam radiation therapy.   The machine delivers high-energy radiation to the brain or brachytherapy, which involves placing radioactive seeds directly into the tumour during surgery
• Chemotherapy: In addition to radiation therapy, chemotherapy could be used to kill the remaining tumour cells. Chemotherapy drugs are usually given intravenously or orally
• Targeted therapy: Some patients may benefit from targeted therapy, which uses drugs that target specific molecules involved in the growth and spread of the tumour. For example, medulloblastoma mutations in the SHH medulloblastoma pathway  use drug treatment that targets this pathway
• Clinical trials: Clinical trials are research projects that explore potential cancer therapies. Patients who take part in clinical trials may get access to cutting-edge techniques inaccessible to the general population. Current clinical trials aim for therapies; effective and safe therapies  to prevent cognitive impairment in children while eradicating medulloblastoma tumours
• Supportive care:  Medulloblastoma patients may need supportive care to manage the symptoms and side effects of the treatment. For instance,  medications; to control pain or nausea, physical therapy to improve balance and coordination, and speech therapy to address speech or language difficulties.

The current advances in treatment have led to improved survival rates for many patients with medulloblastoma. Make sure to talk with the team of healthcare professionals, including a neurosurgeon, radiation oncologist, and medical oncologist, when they develop a personalised treatment plan for you or your loved one to understand potential side effects and the available support groups.

FAQs

How is medulloblastoma diagnosed?

Medulloblastoma  diagnosis is through imaging tests such as magnetic resonance imaging (MRI) or  computerised tomography (CT) scans. 

A biopsy  confirmed the diagnosis and determined the type of medulloblastoma present.³

Can medulloblastoma be prevented?

There is no known way to prevent medulloblastoma.  However,  reducing exposure to radiation at a young age and by doing early genetic testing to diagnose familial gene-disease  may help reduce the risk of developing the tumour.

Who is  at risk of  getting medulloblastoma?

Children and young adults are most  affected by medulloblastoma. In some cases, the tumour may run in the family , due to inherited genetic diseases such as  Turcot’s or  Gorlin syndrome.⁵

How common is medulloblastoma?

Medulloblastoma is a rare tumour.   Accounting for less than 2%  is a malignant brain tumour. It is more common in children than  adults, with most cases diagnosed in children between the ages of three and eight.¹

When should I  consult a doctor?

When a child experiences  persistent symptoms such as headaches, nausea, vomiting, loss of balance, or changes in behaviour or personality, seeking medical attention is step one.³ Your GP can  determine the underlying cause of these symptoms and provide an appropriate referral.

Summary

Medulloblastoma is a malignant brain tumour found in children. The cause of the tumour is unknown but influenced by genetic mutations and radiation exposure. 

Symptoms of medulloblastoma are headaches, nausea, vomiting, loss of balance, dizziness, vision problems, and changes in behaviour or personality. 

Surgery, radiation therapy, and chemotherapy are treatment options. Resources available to help you throughout this journey, including support from your family and community. 

Getting a diagnosis can be emotionally exhausting, and taking care of your mental health is advised. Seeking out a therapist can be incredibly beneficial for your mental health.