Types of tumours
Brain tumours can be benign (non cancerous) or a malignant (cancerous).
Classifications of brain tumours
A benign tumour is non cancerous; these tumours remain confined to the part of the brain where they have formed. Treatment for benign tumours may include surgery and/or radiotherapy treatment.
A malignant tumour is cancerous; these tumours can spread to other parts of the brain. Treatment for cancerous tumours may include surgery, radiotherapy and chemotherapy as a combined treatment plan.Tumours are grouped from grade 1 to 4
benign tumours, where the cells are only marginally abnormal and tend to grow very slowly.
malignant tumours, where the cells appear abnormal in comparison to unaffected brain cells.
malignant tumours, where the cells are significantly abnormal in appearance and actively growing.
malignant tumours, where the cells are highly abnormal and grow rapidly.
Types of brain tumours
Most brain tumours (45%) are gliomas. There are different types of glioma:
- Unspecified glioma (i.e. when the type is unclear or there is a mixture of cells)
Astrocytomas (including glioblastoma multiforme)
Astrocytomas are the most common type of glioma and make up one third of all brain tumours (34%). They develop from cells called astrocytes, which are the cells that support nerve cells in the brain (neurones). High grade (malignant and faster growing) astrocytomas, called anaplastic astrocytoma and glioblastoma multiforme (GBM) are the most common brain tumours in adults.
Oligodendrogliomas are fairly rare, making up 3% of brain tumours. They develop from oligodendrocytes, which are the cells that produce the myelin sheath, a fatty covering over the nerves. Oligodendrogliomas can be benign or malignant (slow or fast growing), usually occur in the frontal or temporal lobes, mostly affect adults and can spread to the central nervous system.
Unspecified or mixed gliomas
If tumour cells are clearly glioma but their type cannot be identified, it is called an unspecified glioma. If it contains more than one type of glioma cell, it may be called an unspecified or mixed glioma. These make up 6% of all brain tumours. If there is more than one type of glioma, the different types might be different grades within the tumour. In this case you will probably receive treatment matched to the most aggressive cells.
Meningiomas occur in the protective membranes that cover the brain (called meninges). They can develop in the membrane of any part of the brain but usually in the cerebellum or cerebrum. They are not normally cancerous but, if they are, they can be aggressive, spreading through the brain and sometimes recurring after removal. Meningiomas make up 25% of adult brain tumours and most commonly affect women and older people.
Craniopharyngiomas usually occur near the pituitary gland at the base of the brain. They are normally benign but their location means they often press on important structures, causing problems with hormones, eyesight, etc. Craniopharyngiomas usually affect young people but are very rare; approximately 12 people a year are diagnosed with it in the UK.
Germ cell tumours+
Germ cell tumours, also called embryonal tumours or germinomas, develop out of primitive cells that originally form in the embryo and create the reproductive system. They make up 2% of all brain tumours and, of these, half affect people between 10 and 20 years old. Germ cell tumours usually affect the chest or abdomen but, if they do develop in the brain, generally occur around the pituitary and pineal glands. They can block the circulation of fluid around the brain, causing symptoms whilst the tumour is still relatively small. Early symptoms and a diagnostic blood test allow for an early diagnosis of many germ cell tumours.
Pituitary tumours are usually adenomas, i.e. they develop out of the tissue of the pituitary gland itself. These tumours normally grow slowly and don’t usually spread. They most commonly occur in older people and make up 8% of all brain tumours.
Uncertain or unknown brain tumours+
Like unspecified gliomas, these tumours are ones that cannot be identified. This may be because it is located in a part of the brain that cannot be operated on. About 14% of brain tumours are ‘unknown’.
Secondary tumours or metastases+
Cancers can spread from their primary site (where they first occur) to the brain. Lung, breast, bowel, kidney (renal) and skin (malignant melanoma) are the cancers most likely to spread to the brain.