BRAIN TUMOURS
( By JASCAP )

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Brain Tumours

Introduction

This booklet is for you if you have or someone close to you has a brain tumour.

If you are a patient your doctor or nurse may wish to go through the booklet with you and mark sections that are particularly important for you.

What is cancer?

The organs and tissues of the body are made up of tiny building blocks called cells. Cancer is a disease of these cells.

Cells in different parts of the body may look and work differently but most reproduce themselves in the same way. Cells are constantly becoming old and dying, and new cells are produced to replace them. Normally, cells divide in an orderly and controlled manner. If for some reason the process gets out of control, the cells carry on dividing, developing into a lump which is called a tumour.

Tumours can be either benign or malignant. Cancer is the name given to a malignant tumour. Doctors can tell if a tumour is benign or malignant by examining a small sample of cells under a microscope. This is called a biopsy.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, if they continue to grow at the original site, they may cause a problem by pressing on the surrounding organs.

A malignant tumour consists of cancer cells that have the ability to spread beyond the original area. If the tumour is left untreated, it may spread into and destroy surrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system - the body's natural defence against infection and disease. It is a complex system made up of organs, such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes (or glands) throughout the body are connected by a network of tiny lymphatic ducts.

When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or metastasis.

It is important to realise that cancer is not a single disease with a single type of treatment. There are more than 200 different kinds of cancer, each with its own name and treatment.

Types of cancers

Carcinomas

The majority of cancers, about 85% (85 in a 100), are carcinomas. They start in the epithelium, which is the covering (or lining) of organs and of the body (the skin). The common forms of breast, lung, prostate and bowel cancer are all carcinomas.

Carcinomas are named after the type of epithelial cell that they started in and the part of the body that is affected. There are four different types of epithelial cells:

  • squamous cells - that line different parts of the body, such as the mouth, gullet (oesophagus), and the airways
  • adeno cells - form the lining of all the glands in the body and can be found in organs such as the stomach, ovaries, kidneys and prostate
  • transitional cells - are only found in the lining of the bladder and parts of the urinary system }
  • basal cells - that are found in one of the layers of the skin.

A cancer that starts in squamous cells is called a squamous cell carcinoma. A cancer that starts in glandular cells is called an adenocarcinoma. Cancers that start in transitional cells are transitional cell carcinomas, and those that start in basal cells are basal cell carcinomas.

Leukaemias and lymphomas

These occur in the tissues where white blood cells (which fight infection in the body) are formed, i.e. the bone marrow and lymphatic system. Leukaemia and lymphoma are quite rare and make up about 6.5% (6.5 in 100) of all cancers. Sarcomas Sarcomas are very rare. They are a group of cancers that form in the connective or supportive tissues of the body such as muscle, bone and fatty tissue. They account for less than 1% (1 in 100) of cancers.

Sarcomas are split into two main types:

  • bone sarcomas - that are found in the bones
  • soft tissue sarcomas - that develop in the other supportive tissues of the body.

Others forms of cancer Brain tumours and other very rare forms of cancer make up the remainder of cancers.

The brain - structure and function

The brain, together with the spinal cord, makes up the central nervous system. This is the 'control centre' which coordinates the body's functions.

Between the surfaces of the brain and the skull there are three layers of membrane called the meninges, which completely cover the brain and spinal cord. Between two of these layers is a space called the subarachnoid space. The subarachnoid space contains a fluid called cerebrospinal fluid (CSF).


Diagram showing the different structures of the brain

Types of brain cells

Like every other organ in the body, the brain is made up of cells. There are about 40 billion nerve cells, also called neurones, within the brain. Everyone is born with a similar amount. Unlike other cells, nerve cells are not able to replace themselves. In fact, as we get older there is a gradual decrease in their number.

The nerve cells communicate with each other and other parts of the body by sending messages (nerve impulses) through a system of nerve pathways or networks.

The nerve cells are held in place and supported by glial cells. There are different types of glial cells, including astrocytes, oligodendrocytes and ependymal cells.

Main structures and functions of the brain

The main parts of the brain are:

  • the cerebrum (the forebrain) made up of the right and left cerebral hemispheres
  • the cerebellum (the hindbrain)
  • the brain stem.

Cerebrum This is the largest area of the brain and is concerned with all higher mental functions, such as thinking and memory. It's made up of two halves or hemispheres. The right cerebral hemisphere controls the left side of the body and the left cerebral hemisphere controls the right side of the body.

Each cerebral hemisphere is divided into four areas, known as lobes: the frontal, parietal, temporal and occipital lobes. Each lobe controls a different range of activities.

Cerebellum This is the back part of the brain and is concerned with balance and coordination. These activities are carried out automatically (subconsciously) by this area of the brain and are not under a person's control.

Brain stem This controls the basic functions essential to maintaining life, including blood pressure, breathing, heartbeat, eye movements and swallowing. It's the bottom part of the brain and connects the cerebral hemispheres to the spinal cord. '> The lobes and functions of the brain

Primary and secondary brain tumours

Primary brain tumours

Primary brain tumours are tumours that start in the brain and have not spread there from somewhere else in the body.

Benign brain tumours

These are tumours that remain in the part of the brain in which they started and don't spread into and destroy other areas of the brain. They do not spread to other parts of the body. If a benign tumour can be removed successfully it should not cause any further problems.

However, sometimes it's difficult to remove the tumour because of its position within the brain, or because the surrounding brain tissue could be damaged by surgery. Some benign tumours will regrow slowly and, if this happens, treatment with radiotherapy or further surgery may be needed.

Malignant primary brain tumours

These are most likely to cause problems by spreading into the normal brain tissue which surrounds them and causing pressure and damage to the surrounding areas of the brain. These tumours rarely spread outside the brain to other parts of the body.

Secondary brain tumours

A secondary brain tumour is a tumour in the brain that has occurred because cancer cells from a cancer in another part of the body have spread to the brain.

Your doctor will be able to tell you if your brain tumour is a primary or secondary tumour.

Risk factors and possible causes of brain tumours

How common is Brain Tumour in India?

The incidence (newly diagnosed cases of cancer in a year) of Brain Tumours in India is about 2 patients per 1,00,000 population, while the morality rate (deaths due to brain cancer) is a little less than 2 patients per 1,00,000 population.

In the year 2006 at TATA Memorial Hospital in Mumbai, India 372 people were diagnosed with Brain and Central Nervous System Tumours, out of which 250 (67%) were males and 122 (33%) were females.

What Causes Primary Brain Tumours?

The cause of most primary brain tumours is unknown, research into this is ongoing. Brain tumours, like other tumours, are not infectious and can't be passed on to other people. They are slightly more common in men than in women.

Age

Although brain tumours can develop at any age, as with a lot of tumours, people are more likely to get them as they get older. Some types of brain tumour, however, are more common in younger adults. Children can also develop brain tumours. We have separate information about brain tumours in children.

Genetic conditions

Brain tumours are not caused by an inherited faulty gene that can be passed on to other family members.

A small number of brain tumours occur in people who have certain genetic conditions, such as neurofibromatosis type 1 and type 2, tuberous sclerosis, or the following syndromes:

  • Li-Fraumeni
  • Von Hippel-Lindau
  • Turcot's
  • Gorlin.

For more information about these conditions you can contact our cancer support specialists.

Previous radiotherapy treatment

People who've been exposed to radiation to their head, such as children who had radiotherapy to the head for leukaemia, are at a slightly higher risk of developing a brain tumour than others.

Other unproven causes Other factors, such as mobile phones, power lines and certain viruses, have been suggested as possible causes of brain tumours. A lot of research has looked into these possible causes, especially mobile phones. However from the evidence to date we still can't say for sure that they cause or increase the risk of developing a brain tumour.

The cause of a secondary brain tumour is always a primary cancer somewhere else in the body.

 
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