Conditions > Brain Tumours

Brain Tumours

Clinical picture

Usually, there are two cancer types that can occur in the brain. A primary brain tumour develops within the brain itself. But many brain cancers are the result of metastasising cancers elsewhere in the body, most commonly the lungs.

The brain is the organ that makes people think, speak and move, but also governs all involuntary physical processes. The brain consists of three main parts.

1: The cerebrum: the largest part of the brain is where functions such as thought, learning ability, problem solving, emotion, speech, language and others reside.

2: The cerebellum: this part is found at the back of the head and coordinates movement, balance and posture.

3: The cerebral cortex: this part connects the brain with the spinal cord. Also known as the reptile brain, this is where primary bodily functions are governed, such as respiration, heart rate, sleep and sensory functions.

In most tumour types there is a clear distinction between benign and malignant growths, but in brain cancer the distinction is often blurred. Benign tumours can be life-threatening, depending on what section of the brain they manifest themselves in. Treatment can be just as challenging as of a cancerous tumour.

Brain tumours occur in the three following stages:

grade I: mostly benign tumours
grade II and III: tumours that are neither benign nor malignant
grade IV: malignant tumours that can spread to other organs and tissues

Glioma

A glioma is a tumour that develops in the glial cells: cells that help form the structure of the brain. There are several types of glioma, each with different symptoms and outcomes.

The main glioma types in adults are:

ependymomas: ependymal cells
astrocytomas: astrocytes (glioblastoma multiforme is a malignant astrocytoma and the most common primary brain tumour among adults)
oligodendrogliomas: oligodendrocytes
brainstem glioma: develops in the brain stem
optic nerve glioma: develops in or around the optic nerve

Brainstem and optic nerve glioma are very rare in adults and occur mostly in children, as a pilocytic astrocytoma. Brainstem glioma is a very aggressive cancer in the brainstem, with a very poor survivability rate: almost all children die within a year from diagnosis.

An optic nerve glioma grows from the optic nerve and can cause problems with sight but also with hormone balance and growth. Its outlook is better: roughly 90% of all diagnosed children are still alive after five years. A pilocytic astrocytoma is a tumour in the cerebellum, which can be surgically removed.

Meningioma

A meningioma is a tumour that grows from the brain membrane and not the brain itself. Almost all meningiomas are benign and slow-growing. In many cases, a meningioma is untreated until symptoms begin to impact a patient’s quality of life.

Primitive neuro-ectodermal tumour

This is a cancer that mostly occurs in children, only 1 or 2% of all incidences concerns adults. During the embryonal stage, the ectoderm is the part of the zygote that will develop into the brain, skin or nervous system. A tumour that develops here is known as a primitive neuro-ectodermal tumour (PNET). If the PNET is found in the cerebrum, it is called a supratentorial PNET. PNETs are malignant and very difficult to treat. Surgery is often an option but adjuvant chemotherapy and radiotherapy are often deemed necessary to prevent spreading. The outlook is mixed: ten years after diagnosis, little more than half of patients remain alive.

In Belgium, around 800 people are diagnosed with some form of brain tumour annually, mostly glioma. Brain tumours affect men slightly more often than women and is most frequently found in patients over 50 years old. The survival rate is relatively poor, mainly due to the fact that brain tumours are usually detected in a fairly late stage of development. In 75% of cases the cancer is already in stage III at the time of its discovery.

Patients who are diagnosed with a stage I or II tumour have a five-year survival rate of about 70%, but this percentage falls sharply to a mere 8% for stage IV-patients.

Symptoms

Symptoms for brain tumours vary greatly, depending on what part of the brain the tumour impacts. The size and growth rate also influence the nature and severity of symptoms.

There are usually four types of symptoms:

Constant headaches: this is caused by pressure on the brain, due to the growing tumour. The tumour can also cause liquid build-up or blockage of brain fluids.
Changes in cognitive behaviour. The tumour can cause symptoms that the patient may not be aware of himself but that are apparent to people around him. These symptoms involve behavioural changes, loss of inhibitions and memory loss.
Deficits: when the tumour exerts pressure on some parts of the brain, it may cause impaired working of certain senses, cognitive or motoric functions:
- Paralysis: if a tumour grows close to a neural node, a patient may experience loss of control over certain muscle groups. Holding a fork or buttoning a shirt can suddenly become difficult.
- Linguistic problems: a tumour on the left hand side of the brain can cause a patient to forget certain words or become unable to comprehend or formulate language.
- Vision problems: blurred or double vision can occur when a tumour grows close to the optical nerve.
- Hearing problems: when the tumour is located close to the cerebral cortex, patients may experience loss of hearing, tinnitus or balance problems.
- Changes in behaviour: sometimes the tumour grows in the area of the brain that governs emotion or behaviour. Patients can experience things in a different manner or respond differently to emotions. They themselves are often unaware of this, but the people that surround the patient do notice these changes.
Epilepsy: epileptic fits can occur when the tumour causes irritation to the brain tissue. This can lead to seizures and fits that can vary from a few uncontrollable twitches of the hand or foot to a full seizure with severe spasms of arms and legs and even unconsciousness. Tongue-biting and involuntary urination often occur during such severe fits.

Cause

Why and how brain tumours develop is not known, but certain risk-inducing factors have been identified. Electromagnetic radiation is one of them, but it does not occur frequently. It is estimated that roughly 1% of brain tumours are caused by radiation, mostly X-rays.

Diagnosis

On suspicion of a brain tumour, a GP will run some basic neurological tests but will refer a patient to the neurologist for further examination. The neurologist will conduct more extensive tests that involve sight, hearing and balance of the patient, and subsequent MRI or CT scans. Another option is a stereotactic biopsy or a craniotomy. In both instances, a small or large opening is made in the skull that enables a neurosurgeon to remove tissue for further examination.

Treatment

How a brain tumour is treated depends on several factors, such as type, malignancy and degree of advancement, but also its location and whether symptoms impair a patient’s quality of life.

The three possible treatments are surgery, chemotherapy and radiation, or most often , a combination of two or three. Another option is to actively monitor the patient without administering further treatment. This is often the strategy when a tumour has stopped growing and where treating the symptoms is easier and less invasive than treating the tumour itself.

Patients over the age of 60 are often selected for active monitoring rather than surgery, chemo or radiation (which can be very taxing on the elderly). Sometimes a choice is made to counteract the symptoms, and thus improve on the daily quality of life. There are also effective medicines against liquid retention, epileptic fits, nausea and pain. Targeted therapy with PD-L1, CTLA-4 and VEGF inhibitors may be appropriate for some patients, with research ongoing in this therapeutic area.