GUIDE PATIENT de l'INCA - Tumeurs cérébrales
We distinguish :
- The so-called primary brain tumors, which start in the brain itself. There are many different types, and each type often has a different treatment or treatment strategy.
- The secondary tumors (or brain metastases), which come from cancer that started in another organ: the lung, colon, breast, kidneys or skin (mainly melanoma), and which spread to the brain.
Brain tumors are broadly classified according to their aggressiveness.
- Some are not very aggressive. They are made up of cells that grow slowly. A benign brain tumor can simply be monitored radiologically or be removed surgically completely or partially without requiring additional treatment such as chemotherapy or radiotherapy.
- Malignant brain tumors define certain primary tumors as well as all metastatic brain lesions. They are made up of cells that divide relatively quickly. These tumors therefore grow rapidly and can invade and damage important brain structures. They can be treated with surgery, radiotherapy, chemotherapy or a combination of these three modalities.
What are the causes ?
The reasons why a cell continues to multiply and become a tumor instead of disappearing according to “its normal life cycle” are imperfectly understood. A brain tumor can develop from any area of the brain: the cerebral hemispheres, cerebellum, brainstem, and pituitary.
That’s why research is so important. Because it is by better understanding the causes and mechanisms that lead to the appearance of a tumor that we can better treat them or even cure them.
What are the symptoms associated with having brain tumors?
The clinical manifestations of a brain tumor vary widely. They depend in particular on its location, its volume or whether or not there is edema around the tumor. These may be headaches, seizures, dizziness / lightheadedness, motor or sensory disturbances, language disturbances, difficulty understanding, confusion, morning sickness / vomiting or decrease vision, hearing loss….
What types of tumors are common in adults?
The most common primary tumors are gliomas, originating from glial cells (astrocytomas and oligodendrogliomas) and meningiomas.
- Gliomas start in the brain and infiltrate more or less aggressively, while meningiomas originate in the envelopes that surround the brain. A distinction is made between low-grade gliomas which are not very aggressive and evolve slowly and high-grade gliomas which are malignant cancerous tumors. Low-grade gliomas most often progress over time to high-grade lesions.
- Meningiomas compress the brain as it grows inside the cranium but are not in the brain itself. They are most often benign.
Also found among primary brain tumors,
- Lymphomas, produced by cells of the brain’s immune system.
- Ependymomas (tumors that arise from the lining of the brain’s ventricles).
- Neuromas or schwannomas originate from Schwann cells (cells that form the myelin sheath surrounding the axons of a nerve).
- Pituitary adenomas, which develop from the pituitary gland.
But there are many other types of brain tumors that are rarer and sometimes very rare.
The official classification of brain tumors by the World Health Organization (WHO) is carried out according to criteria of cellular origin and their degree of malignancy:
- Neuroepithelial tumors are the most common primary brain tumors. They originate from neurons or cells surrounding neurons (glial cells). They are then part of the glioma family. Some tumors are also mixed, that is, they are made up of a mixture of neurons and glial cells. The most frequent tumors are astrocytic tumors (astrocytoma, anaplastic astrocytoma, glioblastoma, oligodendroglioma).
- Peripheral nerve tumors arise from the sheaths of the peripheral nerves, which are made up of different cells than those found in the brain. These tumors are found in the cranial nerves that emerge from the brain to their target territory and peripheral nerves throughout the body. The most common tumor is the schwanoma or neuroma.
- Tumors of the meninges: the brain is covered with a protective envelope called the meninge and from which can form. The most common tumor is benign meningioma.
- Germ cell tumors are rare tumors that tend to occur in children and young adults and have a germline cell origin, that is, they are the same cells found in the gonads (sex organs).
- Tumors of the sellar region: this is a small, specific region of the brain that sits at the base of the skull and houses a large hormonal center called the pituitary gland. This region can be the source of specific tumors. The most common tumor is pituitary adenoma.
- Tumors of hematopoietic origin originate from blood cells. They occur either in isolation in the brain or in the context of more generalized blood disease. This is lymphoma, for example.
- Metastases are the most common brain tumors. They are malignant and secondary to a tumor from another part of the body (lung, breast, kidney, skin). Tumor cells most often migrate to the brain through the bloodstream. The most common metastases are from lung and breast cancer.
How is a brain tumor diagnosed?
The diagnosis necessarily involves imaging tests. The doctor decides, depending on the situation of each patient, which examinations should be performed:
- A clinical examination.
- Radiological examinations. This is basically MRI. The MRI is the most important test that will give a relatively precise idea of the location and type of tumor. Often and for practical reasons because it is a simpler examination to perform, the MRI is preceded by a scanner or this one is requested secondarily to have informations that the MRI does not provide with precision.
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- Depending on the type of tumor suspected or the area where the tumor is located, other exams may be requested: magnetic resonance spectroscopy, positron emission tomography (PET scanner), functional MRI, MRI tractography , arteriography, electrophysiological tests such as electroencephalogram (EEG), to analyze the electrical activity of the patient’s brain, and evoked potentials (EP), to record the response of the nerve pathways and the brain following stimulation.
- Often the diagnosis is quite obvious on a CT scan and MRI, but sometimes it is not possible to determine the exact nature of the tumor with enough certainty to immediately initiate treatment. A biopsy must then be performed to find out exactly what is the type of tumor. This mainly concerns tumors which are supposed to be primary and which are located in areas of the brain where removing them by surgery is risky.
The tumor sample is analyzed by a specialist doctor, called a pathologist. The analysis usually takes 4 to 8 days.
How are the treatments carried out?
In the majority of cases, a multidisciplinary team meets first to decide on the best strategy to treat a specific brain tumor. In our department, every week, neurosurgeons, neuro-oncologists, radiation oncologists and other specialists (RCP) meet in order to share the medical and radiological datas of the different patients and to propose a treatment plan.
Surgery, performed by neurosurgeons, is used regularly for the treatment of primary tumors and metastases.
It can be curative and aim to cure the tumor or to stabilize the situation. It consists of removing all or part of the tumor. The amount of resection depends on several factors: The location, the nature of the tumor, the surgical risk, the patient’s age, etc. The quality of life after the intervention is the most important element. All these elements are discussed between the neurosurgeon and his patient.
- Radiosurgery (RS), hypofractionnated radiotherapy (HFRT)
Radiosurgery allows a high dose of radiation to be administered with extreme precision in one (RS) or a few sessions (HFRT).
This treatment does not require opening the skull and is painless, which is why it does not require general anesthesia and is performed on an outpatient basis.
This treatment is only for certain types of tumors, certain locations and small tumors.
Radiation therapy, performed by radiation therapists, is frequently used for the treatment of malignant brain tumors, sometimes for benign brain tumors. It can either be an adjunct to surgery and / or chemotherapy, or be used alone.
It consists in directing beams of radiation directly on the tumor and its periphery.
It is done in several sessions, usually between 20 and 30. The sessions are generally performed 5 days a week.
Chemotherapy, delivered by neuro-oncologists, is frequently used in the treatment of malignant brain tumors. It can be an adjunct to surgery and / or radiotherapy.
It is about administering powerful drugs in very specific ways. Currently, there are many chemotherapies. Chemotherapy can be curative and thus aim to cure the tumor or to stabilize the patient’s condition. In this case, the purpose of chemotherapy is to control or reduce the size of the tumor in order to limit complications and other side effects so that the patient can maintain a certain quality of life.
- Drug treatments
Certain drugs are regularly associated with surgery, radiotherapy and / or chemotherapy. The most common are corticosteroids and anticonvulsants.
Around 5,000 new people with primary malignant brain tumors are diagnosed each year in France.
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