A tumour is formed of cells that multiply in an uncontrolled way, taking over the 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, which originate from cells that reside in the brain, and which account for 1% of all cancers, and secondary brain tumours. Secondary brain tumours are much more common and are formed of cancer cells from another organ: the lung, breast, colon, kidney or skin (melanoma), and make up
metastases (the processes by which cancerous cells spread in the body to reach and multiply in organs, beyond the organ initially affected).
There are more than 100 different types of primary brain tumours. The most common are those that develop from the glial cells, or from their precursors, known as gliomas, which include astrocytomas, oligodendrogliomas and glioblastomas. Gliomas rarely cause metastasis in other organs.
Meningiomas, which develop in the meninges between the skull and the brain, are common tumours but are generally not cancerous.
The causes of brain tumours
Brain tumours are not usually hereditary; however, in some cases genetic markers have been identified that very slightly increase the risk of developing this type of cancer in a particular individual.
Cancer tends to be linked to successive mutations in a given cell, and in specific genes responsible for the proliferation of the tumour-forming cells. These mutations are only present in the cancer cells, and not in the body as a whole. They are not, therefore, hereditary.
Brain tumour symptoms and diagnosis
The symptoms of a brain tumour depend on the type of tumour, its location in the brain, its size and its speed of development.
Symptoms that may indicate a brain tumour vary and will depend on the location of the tumour inside the brain and how fast it grows.
A brain tumour can also be discovered after an epileptic seizure. This is the most common way that slow-growing tumours are discovered.
Treatments for brain tumours
As with other cancers, the majority of treatments for brain tumours require surgery, radiotherapy and chemotherapy, depending on each individual case.
Treatment for primary brain tumours, especially gliomas, is difficult for several reasons:
- Their location, which makes options for surgery limited, or even impossible;
- The blood-brain barrier, which isolates and protects the brain from pathogens but also hinders the penetration of anti-cancer drugs;
- The intrinsic resistance of many tumours to radiotherapy and chemotherapy;
- The fragility of brain tissue at high doses of radiotherapy.
However, current research, in terms of basic research to understand the biological mechanisms of tumours, as well as clinical research, should lead to new targeted and personalised therapeutic approaches. Targeted innovative therapies have already proven effective in highly specific sub-groups.
