What is a brain tumour?
As a brain tumour grows, it invades the healthy tissue in the brain, often causing further deterioration. These tumours are not contagious, but neither are they preventable and because of the limited space within the skull, the tumour may place pressure on the brain.
Cancer from other parts of the body can spread to the brain and cause secondary tumours through a process called metastasis. Although it is possible for cancer from anywhere in the body to spread to the brain, it happens most often with cancers of the breast and lung.
Some other tumours grow within the skull but outside of the brain itself. These develop from the coverings of the brain (the meninges) and are known as meningioma. They are usually benign (non-cancerous). Meningiomas and secondary cancers are extrinsic brain tumours. Primary brain tumours can be malignant (cancerous) or benign (non-cancerous), while secondary brain tumours are always malignant (cancerous).
Primary brain tumours
There are many different types of primary brain tumour and most grow within the brain. They are generally named after the type of brain cell from which they are perceived to have originated. Most intrinsic primary brain tumours are generically known as gliomas and grow from glial cells. The most common types of glioma are astrocytoma (which grow from astrocytes) and oligodendroglioma (which grow from oligodendrocytes).
So, what causes brain tumours? This is the million dollar question. The cause of most primary brain tumours is unfortunately unknown, which is why they are so difficult to treat - there are over 120 different types of brain tumour which behave and respond to treatment in different ways.