A tumour is formed by cells that multiply uncontrollably, hijacking surrounding cells and, to varying degrees, disrupting brain function. A brain tumour can develop in any area of the brain.
A distinction is made between primary brain tumours arising from cells resident in the brain, which account for 1% of all cancers, and the much more common secondary brain tumours formed by cancerous cells from another organ: lung, breast, colon, kidney, skin (melanoma) in particular, and constituting metastases (the process by which cancerous cells spread throughout the body to reach and multiply in organs other than the one initially affected).
There are over a hundred different types of primary brain tumour. The most common are those that develop from glial cells or their precursors, known as gliomas, which include astrocytomas, oligodendrogliomas and glioblastomas. Gliomas rarely metastasise to other organs.
Meningiomas, which develop in the meninges between the skull and the brain, are common tumours, but are generally non-cancerous.
Causes of brain tumours
Brain tumours are not generally hereditary, although genetic markers have been identified that very slightly increase the risk of developing this type of cancer in a given individual.
Cancer is generally linked to the occurrence of successive mutations in a given cell and in specific genes responsible for the proliferation of the cells that form the tumour. These mutations are present only in the cancer cells and not in the whole organism. They are therefore not hereditary.
Symptoms and diagnosis of brain tumours
The symptoms of a brain tumour depend on the nature of the tumour, its location in the brain, its size and the speed at which it develops.
The symptoms that may reveal a brain tumour are varied and depend on the location of the tumour within the brain and how fast it grows.
A brain tumour can also be revealed by an epileptic seizure. This is the most frequent way in which slow-growing tumours are revealed.
Traitements des tumeurs cérébrales
As with other cancers, the treatment of brain tumours is essentially based on surgery, radiotherapy and chemotherapy, depending on the case.
The treatment of primary brain tumours, particularly gliomas, is difficult for a number of reasons:
- Their location, which makes surgery limited or even impossible;
- The blood-brain barrier, which isolates and protects the brain from pathogenic substances but limits the penetration of anti-cancer drugs;
- The intrinsic resistance of many tumours to radiotherapy and chemotherapy;
- The fragility of brain tissue to high doses of radiotherapy.
Nevertheless, current research, both basic research to understand the biological mechanisms of tumours and clinical research, should lead to new targeted and personalised therapies. Innovative targeted therapies have already proved effective in very specific sub-groups.
