Brain cancer is a tumour or cancerous growth in the brain. A tumour, whether in your brain or elsewhere, is a mass of cells that reproduce themselves in an uncontrolled way. Tumours can be either benign or malignant.
Benign brain tumours are abnormal collections of cells that reproduce slowly and usually remain separate from the surrounding normal brain. They grow slowly, do not spread to other parts of the brain and can usually be removed more easily than malignant tumours. Malignant tumours reproduce and grow quickly. Their borders are hard to distinguish from the normal brain around them. That is why it is hard to remove them completely without damaging the surrounding brain.
Both benign and malignant tumours are further broken up into different types according to the kind of cell from which the tumour develops.
Benign tumours can be divided into the following:
- chordomas: starting in embryonic cells in the spine or base of the skull nerve
- hemangioblastomas: starting in the blood vessels
- meningiomas: starting in the membrane covering the brain
- osteomas: in the skull bones
- pinealomas: in the pineal gland
- pituitary adenomas: in the pituitary gland
- schwannomas: in the cells that wrap around nerves
There are also some tumour types that can be benign in some cases or malignant in others, such as meningiomas or germ cell tumours.
This article focuses on the malignant (cancerous) brain tumours.
Brain cancers are relatively rare, but they are often deadly. The most common malignant types are called gliomas, where cells called glia (cells which help support the nerve cells) become cancerous. Glioblastoma multiforme is the most common of the gliomas. Glioblastoma multiforme and anaplastic astrocytoma are fast-growing gliomas. Oligodendroglioma, another type of glioma, is also rare, but is most often found in adults. Gliomas make up between 50% to 60% of all brain tumours (malignant and benign) in both children and adults combined.
Medullablastoma, which grows from the cells of the medulla at the base of the brain, is the most common type of brain cancer in children. It usually affects children before puberty.
Finally, sarcoma and adenocarcinoma are extremely uncommon types of brain tumour.