Overview of Malignant Brain Tumour
A malignant brain tumour is a life-threatening growth of abnormal cells within the brain or its surrounding structures. Unlike benign brain tumours, which grow slowly and usually stay in one place, malignant tumours are cancerous. They grow rapidly, invade nearby tissue, and may spread within the brain or spinal cord.
These tumours interfere with critical brain functions. Even small tumours can cause serious issues due to the limited space inside the skull. They can affect movement, memory, speech, and other essential functions.
Malignant brain tumours are either primary, meaning they start in the brain, or secondary (metastatic), meaning they spread from cancer in another part of the body. While brain cancers are relatively rare, they cause a disproportionate amount of disability and cancer-related deaths due to their aggressive nature.
This section provides an overview of malignant brain tumour, including its definition, types, risk factors, symptoms, and classification.
What Is a Malignant Brain Tumour?
A malignant brain tumour is made up of cancerous cells that:
- Grow uncontrollably
- Invade nearby brain tissue
- Resist natural cell death
- May create their own blood supply (angiogenesis)
- Often return after treatment
These tumours can disrupt vital brain functions, depending on their location, size, and type.
WHO Tumour Grading
The World Health Organization (WHO) classifies brain tumours into four grades. Grades III and IV are considered malignant:
- Grade III (Anaplastic tumours): Fast-growing and often recur.
- Grade IV (e.g. Glioblastoma): Highly aggressive with poor survival rates.
Primary vs Secondary Brain Tumours
Primary Malignant Brain Tumours
These tumours originate in the brain or nearby structures like the meninges, cranial nerves, or pituitary gland. Common types include:
- Glioblastoma multiforme (GBM): The most aggressive and frequent brain cancer in adults
- Anaplastic astrocytoma
- Medulloblastoma: More common in children
- Ependymoma
Primary tumours rarely spread outside the central nervous system but grow invasively within it.
Secondary (Metastatic) Brain Tumours
These are more common than primary brain cancers. They develop when cancers from other organs spread to the brain, usually via the bloodstream.
- Common sources: lung, breast, skin (melanoma), kidney, colon
- Often appear as multiple brain lesions
- Treatment must target both the brain tumours and the original cancer
Epidemiology
- Incidence: 7–10 cases per 100,000 people per year worldwide
- Age: Most common in people aged 45–70
- Gender: Slightly more common in men, especially glioblastomas
- Geography: Higher rates in developed countries, likely due to better diagnostics or environmental factors
Risk Factors
Most malignant brain tumours appear spontaneously, with no clear cause. However, known or suspected risk factors include:
- Ionising radiation: From cancer treatment or environmental exposure
- Genetic syndromes:
- Li-Fraumeni syndrome
- Neurofibromatosis type 1 and 2
- Turcot syndrome
- Family history: Rare but possible
- Immunosuppression: Especially in transplant recipients or those with HIV/AIDS
- Previous cancers: Particularly lung, breast, or skin cancer
- Environmental exposure: Pesticides or chemicals (evidence remains inconclusive)
Symptoms and Impact
Symptoms of malignant brain tumours vary based on their size, growth rate, and location. Common symptoms include:
- Persistent or worsening headaches, especially in the morning
- Seizures, even without prior history
- Neurological deficits, such as weakness or speech difficulty
- Cognitive and personality changes
- Visual disturbances
- Nausea or vomiting due to raised intracranial pressure
- Chronic fatigue or drowsiness
These symptoms often cause misdiagnosis, delay in treatment, and emotional distress.
Classification and Grading
The WHO classifies brain tumours using both:
- Histology (appearance of tumour cells)
- Molecular markers (e.g. IDH mutation, 1p/19q co-deletion, MGMT promoter methylation)
This approach offers better accuracy in predicting tumour behaviour and treatment response.
Example:
Glioblastomas are now classified as WHO Grade IV IDH-wildtype, which signals a poorer prognosis.
Diagnostic Challenges
Early symptoms of malignant brain tumours are often vague. Accurate diagnosis may involve:
- MRI with contrast (the gold standard for brain imaging)
- CT scans, especially in emergencies
- Surgical or needle biopsy to obtain tissue
- Lumbar puncture, particularly for medulloblastoma
- Genetic and molecular testing of tumour samples
Delays in diagnosis are common, especially in older adults, where symptoms may mimic ageing or dementia.
Prognosis and Outcomes
Survival rates depend on tumour type, location, and how early treatment begins.
- Glioblastoma: Median survival is 12–15 months with standard care
- Anaplastic astrocytoma: Survival of 2–3 years
- Medulloblastoma (children): 5-year survival rate of 60–80%
- Secondary brain tumours: Prognosis depends on the original cancer
Even with treatment, high-grade tumours often return. Survivors may live with long-term cognitive or physical impairments.
Psychosocial and Economic Impact
Malignant brain tumours cause significant emotional, physical, and financial strain:
- Many patients require rehabilitation and daily care
- Caregivers often experience emotional burnout
- Families may lose income and face high medical costs
- Survivors can experience lasting cognitive disability, even after remission
Support services, counselling, and financial assistance are crucial for both patients and families.
Summary
This overview of malignant brain tumour highlights its severity, complexity, and impact. These tumours are among the hardest to treat due to their aggressive growth, resistance to therapy, and location in the brain.
Despite advances in surgery, radiotherapy, and chemotherapy, outcomes remain poor for many high-grade tumours. However, ongoing research in molecular biology and targeted therapies holds promise for the future.
In the next section, we will explore the Causes of Malignant Brain Tumour, including known risk factors and emerging research into genetic and environmental links.
