What are Brain Tumours?
Brain tumours are abnormal growths of tissue in the brain. Brain tumours do not usually spread to other parts of the body but can spread into surrounding brain tissue.

The brain is our ‘nerve centre’ which controls what we do. It is made up of four main areas:
• Cerebrum – The cerebrum is made up of two halves or hemispheres. Each hemisphere is divided into four lobes. The right hemisphere controls the left side of the body and vice versa. As well as controlling many of the body’s functions, it processes ‘higher’ mental processes like thought and self awareness.
• Cerebellum – The cerebellum is at the back of the brain underneath the cerebrum. It deals with balance and co-ordination.
• Brain stem – The brain stem is at the bottom of the brain and connects the cerebrum to the spinal cord. The brain stem keeps us alive by regulating breathing, heartbeat, blood pressure and so on. This is a highly delicate area of the brain.
• Pituitary gland – this small area of the brain regulates the body’s hormone production.

The brain is wrapped in three layers of membranes called meninges, and cerebrospinal fluid lies between two of the membranes to protect the brain. Finally the brain is wrapped in the skull.

Brain tumours are named after the type of cell in which they begin. The brain consists of two groups of cell:
    • The neurones –  These cells send messages to other areas of the brain and body creating what we do.
    • The glial cells – These bind and ‘look after’ the neurones.  Glial cells are divided into astrocytes, oligodendrocytes and ependymal cells.

Brain tumours can be either benign or malignant (cancerous). Benign tumours in the brain grow slowly and do not spread to other areas of the brain. However, if they become large and create pressure within the brain, treatment may be needed to relieve the symptoms. Malignant tumours can be primary (have started in the brain) or secondary (have spread to the brain from other areas of the body).

There are many different types of primary brain tumours and they can vary in their grade. The grade of a tumour means how fast growing it is. Those classified as a high grade generally grow faster than those classified with a lower grade. Tumours can also start in any area of the brain. For example, doctors use the term ‘supra tentorial’ to mean located in the top of the brain, and ‘posterior fossa’ meaning located at the back of the brain.

The main types of childhood brain tumour are listed below. 
• Gliomas – These tumours start in the cells that bind the nerve cells of the brain together. Around 60% of childhood brain tumours are gliomas and they are divided into types depending upon which cell the tumour has started in. The main types are:
• Astrocytomas - These can be high grade or low grade tumours. High grade astrocytomas are known as ‘anaplastic astrocytomas’ or ‘glioblastomas’and are most commonly found in the top of the brain.
• Oligodenrogliomas – these can be high or low grade tumours.
• Ependymoma – these are more common  at the back of the brain in childhood
• Medulloblastomas – About 20% of childhood brain tumours are classed as medulloblastomas. These are high grade tumours.

Other types of tumour include primitive neuroectodermal tumours (or PNETs), germ cell tumours and pituitary tumours which begin within the cells of the pituitary gland.

Who do they affect?
Brain tumours are the most common solid tumour of childhood.  Around 20% of children diagnosed with cancer have a brain tumour.
 
What are the symptoms?
Initial symptoms of a brain tumour include headaches which are generally worse in the morning, and sickness. Depending on where the tumour is, other symptoms can include loss of vision or hearing, irritability, changed behaviour and fits. These type of symptoms will vary according to the location of the tumour within the brain.

How are they diagnosed?
Brain tumours are diagnosed using a number of tests. A CT Scan and MRI scan will be used to get a good look at the brain and any tumour inside it. An examination of the eyes will be carried out to show any raised pressure within the brain. The doctor will also take blood tests and possibly hearing and nerve tests.

Brain tumours are very individual and do appear in many different forms. It is crucial for a doctor to identify as best as possible what type of tumour a child has. The tests may take some time, but a clear diagnosis will help the doctor to draw up the best treatment plan.

How are they treated?
In most cases a brain tumour will be treated with surgery. The aim of this is to remove all, or as much of the tumour as possible. In some cases, because of the position and type of tumour, surgery is not possible. This mostly happens when the tumour is ‘diffuse’ – which means it has no clear edges – and next to or within a delicate area of the brain.

Radiotherapy is also used to treat brain tumours. It is used to treat high grade tumours such as medulloblastoma, high grade gliomas and EpendyMoma. It will be given even if these tumours have been completely removed by surgery. Radiotherapy is also used in addition to surgery if it is has not been possible to remove the entire tumour surgically, or if surgery is not possible because of the location of the tumour.

Currently, Consultants are trying to avoid radiotherapy in children under three years old if possible. This is to try and minimise any long term side-effects which are more common if radiotherapy is given to a very young child’s brain. Parent’s can discuss this with their child’s Consultant and each case will vary. If radiotherapy is avoided, chemotherapy may be used to control the tumour until radiotherapy is given when the child is older. Chemotherapy is also used especially when treating high grade gliomas, medulloblastoma, and PNET tumours that are located in the top of the brain

Steroid drugs are given to reduce the swelling around brain tumours. They don’t treat the tumour itself but help relieve some of the symptoms that the tumour causes. Finally drugs to prevent fits are also used.

Side-effects
The treatment of brain tumours does cause side-effects, These are mainly associated with radiotherapy and chemotherapy. The use of steroids can also produce side-effects including a “rounded-looking” face, weight gain and mood swings. These side-effects are only temporary.

After treatment
As more and more children and young adults survive having a brain tumour, more is being learned about the long-term side-effects of their treatment.  Such effects include slowed physical growth, delayed puberty and developed learning difficulties.

Today, measures such as avoiding radiotherapy in young children (whose brains are developing very rapidly and therefore more vulnerable) aim to reduce the incidence of long term side-effects. There are also medical ways to help. For example, if the child’s growth is affected growth hormone can be given. If a child’s ability to concentrate is altered, they can have specialist help at school. Parents can talk to their child’s Consultant about these long term effects who can relate them to the child’s condition.

After treatment
All children will need to be followed-up at an outpatient’s clinic to be monitored. The Consultant will be looking for any signs that the cancer has returned (recurrent cancer) and checking the functions of major organs to make sure that they have not been affected by the cancer treatment.

Source: www.clicsargent.org.uk