The effects of brain tumours depend on where they occur in the brain (for example, weakness on one side of the body, loss of speech, epileptic seizures, progressive headaches).

Brain tumours can be “primary,” if they occur in the brain itself. There are many types of these, ranging from the most benign to the highly malignant. Conversely, brain tumours can also be “secondary,” if they originate in another organ (lung, breast, …). These are metastases, which affect about one third of patients with cancer (nearly 20 000 patients per year develop brain metastases in France).

Brain tumours are treated by surgery, radiotherapy or chemotherapy. Sometimes these treatments cure the disease, even when it is malignant (for example, germinomas, some lymphomas or brain metastases), but their effect is often insufficient to prevent a relapse, which is the major risk. The causes of brain tumours are not well known. Research is mainly focused on specific genetic changes in the tumours. With modern technology, a veritable “molecular identity card” of each tumour can be established (by the analysis of thousands of genes and their transcripts), specific to each patient. By analysing these identity cards, the medical team can identify the “weak points” of a tumour, for example metabolic pathways that are overactive and can be interrupted to inhibit the growth of the tumour. These “targeted therapies” specific to each tumour hold great promise, but their development requires a considerable investment in research in the laboratory (experimental models) and at the patient’s bedside.