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Diagram showing the brain stem which includes the medulla oblongata, the pons and the midbrain (from Cancer Research UK)

Brain tumours is the generic term for a group of about 130 different diseases [cite] that are all caused by the uncontrolled growth of cells within the brain, spinal cord, or elsewhere within the central nervous system. Different types of brain tumour can be either benign or malignant. Although benign tumours tend to stay localised at the site at which they initially arise, they can be fatal if left untreated, and can occasionally become malignant. Malignant tumours are capable of spreading to other regions of the brain and central nervous system.

Brain tumours are generally named after the type of brain or nerve cell from which they developed, or the region of the brain in which they are growing (for example, tumours arising in cells called astrocytes are named astrocytomas, wheras tumours arising in the pituitary gland are called pituitary tumours). The most common brain tumours in adults are gliomas, which develop from cells called glial cells; they account for about 70 per cent of new cases in US adults. In children, the most common form is medulloblastoma [ref].

Cancers that arise elsewhere in the body can also spread to the brain. These are called secondary brain tumours, and tend to behave and respond to similar treatments to the original (primary) cancer type from which they arose.

Brain tumours can cause a diverse range of symptoms, all of which are hard to tell apart from other more common conditions. These are divided into symptoms caused by the physical pressure inside the skull - including fits, persistent headaches and seizures - and others caused when a growing tumour the disruption of normal brain functioning, such as memory, personality and coordination problems.

The causes of brain tumours are still poorly understood. The only environmental cause recognised by the International Agency for Research on Cancer (IARC) is ionising radiation (for example, medical x-rays). The risk of developing the disease generally increases with age. However some forms are more common in children. The disease is also more common in people with certain inherited genetic conditions, such as neurofibramatosis.

Classification

Tumours of the brain and central nervous system are classified by a number of different systems and methods, and according to a number of different attributes.

The World Health Organisation's 'classification of tumours of the central nervous system' classifies tumours according to their location or tissue of origin within the brain or central nervous system. Additionally, after analysis of a tumour sample with a microscope, brain tumours are assigned a grade - from 1 to 4 - indicating the speed of growth and spread. Grade 1 tumours are considered the slowest growing, whereas grade 4 are the fastest.

Cell of origin

Need link to 'List of types' page?

Benign can become malignant

Based on cell type

Traditionally based on appearence down microscope

Now becoming driven by genetics and molecular biology

Signs & symptoms

The symptoms of brain tumours are often hard to differentiate from other more common ailments, as well as other neurological conditions. Broadly speaking, they are divided into two categories - symptoms caused by the physical presence of a mass within the brain or central nervous system; and those caused by the disruption to normal neurological function by the growing tumour.

Symptoms caused by pressure

These include:

• Headaches
• Sickness
• Drowsiness
• Problems with your eyes
• Fits (seizures)

Development

Depends on region in brain, can develop from many cell types.

Diagnosis

Although there is no specific or singular clinical symptom or sign for any brain tumors, the presence of a combination of symptoms and the lack of corresponding clinical indications of infections or other causes can be an indicator to redirect diagnostic investigation towards the possibility of an intracranial neoplasm