Malignant neoplasms of the brain (brain tumors) constitute a large group of various diseases. Brain tumors differ in terms of their causes, symptoms, course and prognosis. Find out about the features of brain tumors, the symptoms of brain tumors, the types of brain tumors, and the diagnosis and treatment of brain tumors.
Brain tumorsin adults account for about 2% of all malignant tumors. In the case of children, brain tumors are the second most common group of malignant neoplasms - they account for as much as 30% of all childhood cancers. Brain tumors are a special group of neoplasms that differ in many respects from neoplasms located in other organs. The most common group of primary brain tumors are gliomas. The types of brain tumors also include meningiomas, craniopharyngioma, ependymomas and medulloblastomas. Intracranial neoplasms are also very often the result of metastases. More than half of all intracranial tumors are metastatic cancer from other organs. For precise nomenclature, it is worth adding that malignant brain tumors should not be called cancer. Cancer is a malignant tumor that originates in epithelial tissue. Most of the primary brain tumors come from other types of tissue, so the term "brain cancer" is wrong - use the terms brain tumor or malignant brain tumor correctly.
Malignant neoplasms of the brain - how do they arise?
Malignant tumors of the brain develop within the central nervous system. It is one of the most unique and the most important systems in the human body. Due to the different anatomy and physiology of the central nervous system, neoplasms that arise within it have specific features that distinguish them from neoplasms in other locations.
The human brain consists of two cerebral hemispheres, the brain stem and the cerebellum. The hemispheres of the brain are responsible for thinking and cognitive processes (memory, concentration, language). The brain stem controls the activities necessary for human survival (breathing, heartbeat, consciousness). The functions of the cerebellum include control of performed movements and a sense of balance.
To understand the great variety of brain tumors, it is worth learning the microscopic basics of itorgan. The human brain is made up of many types of cells. The largest volume of the brain consists of nerve cells (neurons) and glial cells, which support neurons. In addition to them, there are many other types of cells in the structure of the brain:
- connective tissue cells building the meninges,
- epithelial cells producing cerebrospinal fluid,
- pituitary glandular cells
- and many other cells building separate structures of the brain.
Malignant tumors in the brain arise when normal cells are converted into cancerous cells. All of the cells listed above may be the starting point for a brain tumor. This relationship results in a huge variety of brain tumors.
What are the special features of brain tumors?
The first is the high incidence of metastatic neoplasms. Among all brain tumors, as many as 60% are metastatic tumors from other organs (most often the lungs, breasts, colon and kidneys). Only 40% of brain tumors are primary tumors, arising from the tissues of the central nervous system.
Neoplastic metastases to the brain are common, while the opposite situation - the spread of brain tumors outside the central nervous system is rare. Due to the strong isolation of the nervous system from other organs (e.g. via the blood-brain barrier), primary brain tumors practically do not spread beyond the central nervous system.
A special feature of some brain tumors is that they can spread through the cerebrospinal fluid. This is the ability of childhood medulloblastoma, which can metastasize to other parts of the central nervous system (most often to the spinal cord).
Why are brain tumors formed?
The answer to this question remains unknown in most cases. In rare cases, brain tumor development is associated with inherited genetic conditions such as von Hippel-Lindau syndrome, neurofibromatosis, or tuberous sclerosis. Some patients are suspected of being associated with viral infections, including with EBV and HIV.
The risk of a malignant brain tumor is increased in people who, for other reasons, have had in the past irradiation of the head area with ionizing radiation. In the vast majority of patients, the factor responsible for the development of the disease cannot be detected - a brain tumor is the result of a spontaneous transformation (mutation) of a he althy cell into a neoplastic cell.
It is also worth emphasizing that, despite many scientific studies, so farThere was also no clear link between the use of cell phones and the development of brain tumors.
Malignant neoplasms of the brain - symptoms
The symptoms of brain malignancies may be discrete and non-specific at first. As the tumor volume increases, symptoms usually worsen. The human brain is surrounded by a skull - a rigid structure that does not increase in volume.
Brain tumor development is associated with the build-up of extra mass inside the skull, resulting in an increase in intracranial pressure. Early symptoms of this condition include headache and vomiting, especially in the morning. With a large increase in intracranial pressure, disturbances of consciousness may occur.
If the intracranial pressure continues to increase, there is a risk of brain structures displacing towards the spinal canal. This condition, called intussusception, can be life-threatening and requires immediate medical attention.
The symptoms of brain tumors are often related to their location. Every part of the brain has specific functions that can be disrupted by your developing cancer. Some neurological symptoms may suggest a tumor in a given location before imaging tests are performed.
- Brain tumors located in the area of the frontal lobes can cause concentration disorders, personality changes and mental disorders as well as epileptic seizures.
- Tumors of the temporal lobes disturb the interpretation of auditory stimuli.
- The visual center is located in the occipital lobes. A tumor in this area may result in visual field defects and incorrect analysis of visual stimuli.
- Tumors located in the cerebral hemispheres may disrupt the functioning of the motorways, leading to paresis.
It is worth knowing that paresis resulting from a tumor of the central nervous system appears on the side opposite to the location of the tumor. In the case of cancer located on the left side of the brain, the paresis will be in the right side of the body. The reason for this is the course of motor paths, which cross after "leaving" the brain.
The brain stem is the part of the brain where most of the cranial nerves originate. They are responsible, inter alia, for uttering words, eye movements, swallowing and coughing reflexes, and the work of facial muscles.
Neoplasms in the area of the brain stem interfere with these activities. They may appear:
- speech difficulties,
- swallowing disorders,
- asymmetrical facial expressions,
- incorrect position of the eyeballs (nystagmus, strabismus).
In turn, the cerebellum located in the back cavity of the skull is responsible for the precision of movements, the sense of balance and the coordination of all muscles. Tumors located in the area of the cerebellum appear:
- imbalance,
- incoherent movements
- and their loss of coordination.
Hormonal disorders may be a special symptom of brain tumors. Inside the brain are structures that produce different types of hormones. The most important of them are the hypothalamus and pituitary gland, which produce e.g. oxytocin, vasopressin, prolactin, growth hormone and many more.
Cancer growing in these areas can interfere with hormone production. An example of such a situation is diabetes insipidus - a condition resulting from the reduced production of vasopressin.
Diabetic insipidus can be caused by a tumor located near the hypothalamus. Its main symptoms are passing large amounts of diluted urine, resulting in dehydration and electrolyte disturbances.
Malignant neoplasms of the brain - types
The enormous variety of the tissues that make up the brain causes a great variability in the structure of brain tumors. The histopathological examination of the tumor is to determine the type of neoplasm and the degree of its malignancy.
Among brain tumors belonging to a common group, there may be subtypes with different malignancy and prognosis. The degree of malignancy of brain tumors is defined according to the WHO classification from I to IV. Grade I neoplasms are considered benign. The most malignant tumors receive grade IV histological malignancy.
Diagnosing the type of tumor is important in planning treatment, as different types of cancer show different sensitivity to certain types of therapy. The most common type of primary brain tumor is gliomas, which are tumors that originate from glial cells. One of the most common brain tumors in the pediatric population is medulloblastoma, or medulloblastoma.
Gliak
According to various data, gliomas account for 40 to 70% of primary brain tumors. It is a huge group of neoplasms with numerous subtypes. Glia is the supporting tissue that nourishes and supports the function of nerve cells.
There are many types of glial cells that differ in structure and function. This causes a huge variety of gliomas - there are both grade I and highest grade IV gliomas.
The names of different types of gliomas often refer to the appearance of neoplastic cells (astrocytomas,boots).
Gliomas are characterized by extensive infiltration of the surrounding brain tissue, which in many cases makes their surgical removal difficult. Glioblastoma multiforme is characterized by the highest malignancy among all gliomas. It is an unfavorable cancer, classified as WHO grade IV.
Meningioma
A meningioma is a cancer that occurs within the meninges. The vast majority of meningiomas are mild. The meninges surround the brain from the outside, so meningiomas adhere to the tissues of the brain but do not grow inside the brain.
Thanks to this, most meningiomas can be removed during surgery. Malignant meningiomas account for less than 10% of all cases of this cancer. Importantly, meningiomas can develop around the brain as well as the spinal cord.
Czaszkogardlak
The craniopharyngioma is a cancer that results from abnormalities in the embryonic development of the brain. Craniopharyngioma can occur in both children and adults. It is a benign tumor (WHO grade I).
A characteristic feature of craniopharyngioma is its location - craniopharyngiomas are located in the vicinity of the so-called Turkish saddle. It is the part of the brain adjacent to the pituitary gland and the crossing of the optic nerves.
The symptoms of craniopharyngioma result from the influence on these structures. The compression of the pituitary gland causes hormonal imbalances related to the inappropriate release of pituitary hormones.
On the other hand, pressure in the area of the optic nerve junction results in visual symptoms (typically there is bilateral amblyopia in the temporal part of the visual field).
Wyściółczak
Ependymoma belongs to the neoplasms of glial origin. Ependymoma, as its name implies, grows in the tissues that line the cerebral ventricles and the spinal cord canal. These spaces in the brain are filled with cerebrospinal fluid.
The presence of ependymoma in their vicinity may cause disturbances in the circulation and drainage of the cerebrospinal fluid. This situation leads to an increase in intracranial pressure, which often results in the first symptoms of ependymoma (headaches, vomiting).
Complete blockage of CSF due to ependymoma can lead to hydrocephalus.
Medulloblastoma
Medulloblastoma is one of the most common malignant brain tumors among children and adolescents. A typical localization of medulloblastoma is the posterior-lower parts of the brain, particularly the cerebellum.
Cerebellar tumors causetypical clinical symptoms: balance and gait disturbances, and loss of coordination. C
an echo that distinguishes medulloblastomas from other brain tumors is the ability to metastasize through the cerebrospinal fluid. Medulloblastoma can spread to both the higher parts of the brain and towards the spinal cord. Medulloblastoma is a grade IV neoplasm according to WHO.
Tumor metastases
The examples described above concern primary brain tumors - their starting point is the tissues that build the brain. However, it is worth remembering that more than half of all intracranial tumors are metastatic tumors from other organs. The most common tumors that spread to the brain include: breast cancer, lung cancer, kidney cancer and colorectal cancer.
How do you know if the tumor found in the brain is of a pyogenic or metastatic nature? Clinical data always provide a clue: if a patient is treated for a previously diagnosed tumor, the tumor detected in the brain is likely to be metastatic.
The final answer is given by the histopathological examination of a fragment of the tumor. By viewing the tumor tissue under a microscope, the pathologist is able to determine the source of the tumor.
Malignant neoplasms of the brain - diagnosis
Diagnostics of brain tumors begins with a medical interview. Symptoms that give rise to a suspicion of a brain tumor are an indication for a quick diagnosis. The physical examination should include a complete neurological examination (assessment of muscle strength, sensation, balance, examination of cranial nerves), as well as an ophthalmological examination with an assessment of the visual field.
The fundus examination is useful in diagnosing the elevated intracranial pressure that is common in brain tumors. Any suspicion of a brain tumor requires head imaging. The CT (computed tomography) test is most often performed first, due to its high availability and speed of execution. Computed tomography allows you to visualize abnormal structures within the brain and estimate their size.
In order to obtain a more accurate image of the tumor, it is necessary to perform magnetic resonance imaging (MR), which shows the soft tissues much better. Some brain tumors are so distinctive that they can be identified with high probability only by imaging tests.
The final diagnosis of the type of neoplasm requires a histopathological examination. For this purpose, a biopsy is most often performed, i.e. a small fragment of the tumor is taken. Early histopathological diagnosis is an important factor influencing the choicetreatment regimen.
In some cases, material obtained only during tumor removal surgery is sent for histopathological examination.
Malignant neoplasms of the brain - stages
The stage of cancer at the time of its diagnosis is one of the most important factors determining the prognosis of a given patient. In the case of most cancers, the stage is determined by 3 basic features:
- tumor size,
- lymph node involvement
- and the presence of distant metastases.
These criteria are slightly different for brain tumors. The size of the brain tumor plays a prognostic role and influences the severity of the disease symptoms. However, an equally important feature is the location of the tumor and the way it grows.
A good example is meningiomas, which are most often located on the outside of the brain and well separated from it, which makes their surgical removal much easier.
Neoplasms with infiltrative growth, which penetrate deep into the brain tissues, have a much worse prognosis. These types of tumors are virtually impossible to remove completely - their excision is associated with too high a risk of irreversible brain damage.
The WHO grade classification is also used to assess the advancement of brain tumors. According to it, the mildest tumors receive grade I, and the most malignant - grade IV.
It is worth remembering, however, that histological malignancy is only one of the parameters of the cancer. The specific location of brain tumors significantly influences their clinical course. There are situations in which relatively benign neoplasms are severe and have a serious prognosis (for example, due to the location in the vicinity of the so-called vital centers, i.e. the most important structures of the human brain).
Malignant neoplasms of the brain - treatment
Treatment of malignant brain tumors is based on two assumptions: destroying or removing as much of the tumor as possible, while saving the rest of the brain.
In the treatment of most cancers, the most effective method of treatment is surgical removal of the tumor with a wide margin of he althy tissue. This principle is impossible in the case of brain tumors.
A person is able to survive and function without a single kidney, without a large part of the liver or lung, and after removal of sections of the intestine. Cutting out or damaging even small pieces of a he althy brain carries the risk of serious complications. For this reason, local therapy for brain tumors (surgery, radiotherapy) is a musttargeted nature - when removing a neoplasm, it is necessary to take care of as little damage to nearby tissues as possible.
One of the most important stages in the treatment of brain tumors is the surgical removal of the tumor. Unfortunately, surgical treatment of tumors in this area is associated with numerous limitations. Some brain tumors are inoperable from the outset. Some parts of the brain cannot be reached without damaging the structures responsible for vital functions. For this reason, it is impossible to operate on many tumors located, for example, in the area of the brain stem.
The complete removal of the neoplasm is decisive for the effectiveness of surgical treatment. It is technically easiest to remove tumors that are compact and clearly demarcated from nearby parts of the brain. Surgery to remove infiltrating and diffuse growing neoplasms is much more difficult.
Complete excision of the tumor is impossible in such cases. Nowadays, many neurosurgical operations are performed using modern technologies that allow for intraoperative monitoring of brain functions. The so-called mapping allows you to locate important parts of the brain (centers of speech, movement or hearing) in order to avoid their damage during the procedure.
Radiotherapy remains an important method of treating brain tumors. Currently, irradiation of the entire brain is used less and less (with the exception of certain types of neoplasms, e.g. brain lymphomas). Modern radiotherapy of brain tumors enables the radiation beams to be directed directly to the tumor area, sparing the remaining parts of the brain. This type of radiation is called stereotaxic radiotherapy.
For several years, treatments using the Gamma Knife tool, operating on the basis of stereotaxic radiotherapy, have been available in Poland. This form of therapy can be used in some patients who cannot be treated surgically due to the difficult location of the tumor. Qualification for this method of treatment requires meeting certain conditions (including the appropriate shape and relatively small size of the tumor).
Compared to surgery and radiation therapy, chemotherapy plays a much smaller role in the treatment of brain tumors. Many brain tumors are not sensitive to chemotherapy.
Another problem is that drugs reach the brain area. The blood-brain barrier does not allow a large proportion of substances in a patient's bloodstream to pass through, including most medications.
Chemosensitive neoplasms include, among others lymphomas, oligodendrogliomas and spores. For tumors belonging to these groups, chemotherapy is usedone of the basic elements of treatment.
Brain cancer and its treatment may be associated with bothersome symptoms. In addition to essential anti-cancer therapy, many patients require appropriate supportive care. One of the common complications of the disease are seizures. They can be the result of both the presence of a tumor and scarring of the brain tissue caused by surgery or radiation therapy.
Sometimes the symptoms of epilepsy regress with successful cancer treatment. Some patients need to take antiepileptic drugs for the rest of their lives. Another complication of brain tumors is brain swelling, which occurs in the postoperative period or during radiotherapy.
The use of these methods of treatment requires appropriate prophylaxis (administration of drugs that prevent cerebral edema - glucocorticosteroids).
Malignant neoplasms of the brain - prognosis
The prognosis of brain tumors depends on many factors. The most important of them are: the degree of histological malignancy of the tumor (from I to IV according to WHO), its location and the possibility of using complete surgical treatment. In the most common primary brain tumors - gliomas - treatment options and prognosis largely depend on the malignancy of the tumor.
For stage I benign neoplasms, the 5-year survival rate is over 80%. As histological malignancy increases, the percentage of complete cures decreases. In stage 2 tumors, the 5-year survival rate is 50-70%, and for the third - 20-45%.
The greatest challenge remains treating gliomas with the highest, fourth degree of malignancy. The most common neoplasm in this group, grade IV glioblastoma, has an average survival time of 14 months.
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