Tumors of the brain

Tumors of the brain are, according to various data, 2-8.6% of the total number of all human tumors. Among the organic diseases of the CNS, 4.2-4.4% occur on the tumor. The number of newly diagnosed CNS tumors annually increases by 1 - 2%. At the same time in adults the death rate due to brain tumor ranks 3-5 among all causes of death. In children, the lethality due to the development of the oncological process of the central nervous system ranks second after the diseases of the hematopoietic and lymphatic systems.

Epidemiology

In Ukraine, the frequency of brain tumors in men is 10.2 per 100 thousand of the population. Among women, this figure is 7.6 per 100 thousand. In the United States, the frequency of brain tumors among men is 12.2 per 100,000, and among women, 11 per 100,000. The number of brain tumors in women aged 40-50 years is 1.5 - 1.8 times higher than in men. In men, mainly glial tumors are found, whereas meninhyomas and neurinomas predominate in women.

The distribution of neoplasms according to the histological structure largely depends on the average age of the patients of the sample studied. Thus, in adults 40-45% of primary tumors are gliomas, 18-20% - meningiomas, 8% - neurinomas of the VIII nerve, 6-8% - adenomas of the pituitary gland, in children gliomas account for 75% of all tumors; meningiomas - 4%, whereas neurinomas and adenomas are extremely rare. In patients older than 70 years, 40% of brain tumors are meningiomas.

Recently, there has been a trend towards an increase in the incidence of metastatic brain tumors of this type.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]

Causes of the brain tumors

The basis of the development of brain tumors, like any other localization, is a persistent violation of the integrity of the genetic apparatus of the cell, especially those parts of it that are responsible for controlling the initiation and progression of the cell cycle. Genes that encode protein factors that constitute the basis of the mechanism of cell division progression (Hb, E2F, cyclins and cyclin-dependent protein kinases), signal transduction proteins (for example, the Ras cascade), growth factors (eg, PDGF) and their receptors , as well as factors depressing the development of the cell cycle and activating the cascades of apoptotic cell elimination, with the defects of loci associated with the regulation system of the progression of the cell cycle leading to overexpression of mitotic activity promoters or to the emergence of new persistent pathological forms of promitotic factors with increased functional activity. While the damage to the genes of the apoptotic system in the context of oncogenesis is a fallout.

At the present time, data have appeared that suggest that primary genetic damage occurs in cells with active expression of the cell cycle regulation apparatus, that is, in mitotically active cells. The increased activity of the mitotic apparatus of the cell leads to its division, and the genetic information is retained in the tissue, while the increased apoptotic activity leads to elimination of the cell and destruction of all deviations of the cellular genome. But specialized tissue progenitors, tissue stem cells can for a long time remain in a state between apoptosis and mitosis, which opens the possibility of a gradual degeneration of genetic loci, both mitotic and apoptotic systems, with the possibility of transferring emerging defects to subsequent cell generations.

An important condition for the transition of a proliferating cell from a discharge with increased mystical activity to a discharge with uncontrolled mitotic activity is the gradual accumulation of a number of mutational changes in the genome of the cell line. Thus, the development of astrocytic glioma and its degeneration into a malignant form - glioblastoma - is accompanied by the accumulation of mutational changes in the genome of tumor cells. It is now established that mutations in chromosomes 1, 6, Er, lGq, lip, 13q, 14, 17p, 18, 19q, 22q are the key moment of the onset and progression of the main types of brain tumors.

The mutational degeneration of genetic loci can occur for various reasons. It should be noted that some of them may have a direct damaging effect on the genome of brain cells. Another group consists of factors that indirectly increase the transcriptional load on these genes or reduce the activity of the genetic repair system.

In sum, its combination of several negative factors against the background of an innate predisposition, which can acquire expression in various genetic deviations, leads to a violation of the integrity of the genetic information of the mitotically active cell, which is the primary event on the path of oncogenic degeneration. The imbalance of the system of genetic transcription, repair and replication, which inevitably arises, increases the vulnerability of the genome of the cell clone, which increases the likelihood of subsequent mutational events.

Among the unfavorable factors in this respect, it is necessary to isolate ionizing radiation, electromagnetic field, pesticides and other factors of chemical contamination of the environment.

Important is the carriage of oncogenic viruses, which can provoke or promote the progression of the described processes. These should include viruses Epstein-Barr, human papilloma (type 16 and 18), HIV, etc.

Harmful habits, like the "dietary" factor, for a long time refer to a group of classic factors that increase the risk of oncological diseases. In this regard, brain tumors are no exception.

At present, the effect of the transplantation of CCT on the possible development of a brain tumor should be considered more hypothetical, since the corresponding temporary combination of both pathologies of the brain is extremely rare and belongs to the category of random findings.

Given the great predisposition of representatives of different sexes to the emergence of certain variants of brain tumors (for example, meningiomas are more common in women), it is advisable to consider the effect of sex hormones in the progression and, possibly, in increasing the likelihood of occurrence or even the emergence of primary tumor lesions.

Finally, the presence in close relatives of tumors of the nervous system or diseases such as, for example, Recklinghausen's disease, increases the risk of developing a brain tumor.

[11], [12], [13], [14]

Symptoms of the brain tumors

From the pathogenetic point of view, the primary importance and development of clinical symptoms is an increase in tumor volume, which leads to direct and indirect development of the syndrome of increased intracranial pressure and the whole gamut of focal symptoms.

The formation of hypertensive syndrome occurs for a reason. First, the growth of the tumor focuses to an increase in the volume of the tissue component in the cranial cavity. Secondly, with a certain location of the tumor, a disturbance of the outflow of the CSF is possible, which leads to an increase in its volume in the cavities of the ventricular system.

And finally, thirdly, the expansive growth of the tumor in certain cases can cause compression of the surrounding brain tissue, including the vessels of different calibres, which determines its ischemia, a decrease in ATP production, a disruption in the work of ATP-dependent ion exchangers, which maintain a normal balance ions between tissue compartments (intracellular medium, intercellular space, vascular bed). The latter is accompanied by an increase in the osmolality of the extravascular environment and the accumulation of water in the ischemic foci of brain tissue. The rapid development of edema-swelling of the brain tissue initiated along the periphery of the tumor node may be the main factor for the further spread of this process and the involvement of ever larger areas of the brain.

Compression of immediately adjacent to the tumor focus areas of the brain leads to the development of focal symptoms. Compression of areas of brain tissue located at a certain distance from the tumor, under the influence of the spreading process of swelling-swelling, ischemia or due to tumor growth leads to the appearance of symptoms at a distance. In the most far-advanced case, conditions are created for the dislocation of brain tissue and the formation of wedging syndromes.

Local compression of the brain tissue or increased intracranial pressure and irritation of the receptors of the meninges becomes possible due to the constant volume of the cranial cavity. According to the Monroe-Kelly doctrine, the volume change of one of the three components of the cranial cavity (tissue, blood, liquor) . Tumor growth primarily leads to a local decrease in blood flow and is accompanied by a decrease in the volume of CSF in the cranial cavity. Reduction of blood volume in the cranial cavity has significant consequences, as a rule, aggravating the perfusion situation in the brain tissue. Taking into account the mechanism of the development of edema-swelling of the brain, it can be foreseen that the state of compensation will sooner or later be violated and this will lead to the emergence of a vicious circle: ischemia - edema - increased tissue pressure - ischemia.

The described pathogenetic features of the development of the tumor process explain, on the one hand, the possibility of prolonged growth of the tumor in the functionally inert regions of the brain in the absence of severe symptoms, and on the other, the presence of brain tumors that, even with small dimensions and a limited period of growth, give marked clinical symptoms.

In clinical terms, the general cerebral and focal brain tumor symptoms that arise in connection with the development of the brain tumor are isolated.

The main and one of the earliest symptoms of the development of intracranial hypertension due to tumor growth is headache. This symptom is observed in 92% of patients with subtentorial and in 77% - with supratentorial tumors and occurs due to tension and compression of the dura mater. At the beginning of the disease, the headache is often of a diffuse nature, dull, unstable, bursting.

As the intracranial pressure rises, the pain intensifies, acquires a permanent character. A characteristic but not constant feature of the headache resulting from the development of intracranial hypertension is its occurrence or enhancement in the second half of the night, in the morning, which is associated with an increase in cerebrospinal pressure during this period of the day. Sometimes, against a background of constant headache, there is a seizure-like gain, which is accompanied by vomiting, dizziness, lowering of the level of consciousness.

Typical for brain tumors should be considered the emergence or intensification of headache during excitement, physical stress. The connection between the intensity of pain sensations and the position of the patient's head in patients with IV ventricles is classified as classic: the pain decreases with the patient's position on the side of the tumor localization (the Vruns symptom), which is explained by the gravitational displacement of the tumor node. At the same time, in elderly people, even if there is a large tumor, the pain symptoms may be absent for a long time. In benign neoplasms of the meninges, the pain is of a local nature, sometimes irradiating into specific zones and with superficial location of the tumor node may be accompanied by local soreness with percussion. However, such variants of pain symptomatology are less significant in the setting of a preliminary diagnosis.

Vomiting occurs in 68% of patients with brain tumors. Most often this symptom of a brain tumor is associated with the development of intracranial hypertension, but it can sometimes be caused by the presence of a tumor in the region of the IV ventricle or cerebellum, which has a direct mechanical effect on the vomiting center. A classic characteristic of so-called tumoral vomiting is its occurrence in the morning hours, without prior nausea, on an empty stomach and at the height of the headache. After vomiting, the intensity of the headache decreases with time, which is associated with an upcoming dehydrating affect and a decrease in intracranial pressure. The frequency of vomiting is variable.

A frequent neuro-ophthalmologic symptom, which reflects the presence of intracranial hypertension, is congestive discs of the optic nerves. In most cases, this symptom is detected simultaneously from both sides, but sometimes its appearance may differ in time. The rate of development of this symptom depends on the rate of increase within the cranial hypertension. Stagnation of optic discs is most often determined in combination with other hypertensive symptoms. And only in certain cases (for example, in children) the symptom can be the character of the debut.

Increase in intracranial pressure leads to disturbances in the activity of the peripheral parts of the visual analyzer, which is primarily due to the swelling of the optic nerve tissue and the retina of the eye. Subjectively, the patient notes the periodic occurrence of the veil before the eyes, "flies" in the early hours. A prolonged increase in intracranial pressure leads to the development of secondary atrophy of the optic nerves.

At the same time, the reduction in visual acuity resulting from the development of atrophy is irreversible. Carrying out radical surgery or prolonged normalization of intracranial pressure often does not lead to a halt in the progression of vision loss. In the case of the development of the tumor process in the anterior or middle cranial fossa, compression of the optic nerve on the side of the tumor often observes F. Kennedy's symptom: the combination of primary optic atrophy on the side of tumor growth with secondary atrophy of the opposite optic nerve due to the development of hypertensive syndrome.

Vertigo is observed as a cerebral symptom with intracranial hypertension in 40-50% of patients with brain tumors. The appearance of this symptom is associated with the development of stagnant phenomena in the vestibular labyrinth and an increase in Endolymph pressure in the semicircular canals. In some cases, it can manifest as an element of focal symptomatology in tumors of the cerebellum, VIII nerve, bridge and IV ventricle.

Patients describe the symptoms as a feeling of rotation of surrounding objects and their own body, a sense of failure. Dizziness, arising due to intracranial hypertension, is manifested in later stages of the development of the pathological process. In any case, this symptom arises, as a rule, paroxysmal, often after a significant increase in intracranial pressure. Often dizziness is accompanied by nausea, vomiting, noise in the ears, vegetative disorders and even a decrease in clarity of consciousness.

Disorders of the psyche in the context of the development of cerebral cerebral symptoms are found in 63-78% of patients. As the main pathogenetic moments in the development of this type of disturbance, it is necessary to consider the violation of blood perfusion of the brain tissue, especially its stem sections, which is a direct consequence of the increase in intracranial pressure, cerebral intoxication by the decay products and factors that are produced in the tumor site, as well as diffuse violation function and anatomical integrity of the associative pathways of the brain. It should also be noted that mental disorders are elements of focal symptomatology in tumors of the frontal region. In this case, the development of mental disorders of the patient occurs under the influence of both cerebral and local pathogenetic mechanisms.

The nature of mental disorders that occur with brain tumors may be different. So, against the backdrop of a clear consciousness, the occurrence of memory disturbances, thinking, perception, the ability to concentrate. In certain cases, aggressiveness, a tendency to unmotivated behavior, manifestations of negativism, a reduction in criticality comes to the fore. Sometimes such symptoms of a brain tumor can be displaced by a phase of apathy, lethargy. In some cases, there is a development of delusional state and hallucinations.

In elderly patients, the development of mental disorders almost always accompanies an increase in intracranial pressure and is often the earliest clinical sign, especially in the presence of hypertension and atherosclerosis.

The level of consciousness is the main clinical equivalent of perfusion of the brain with blood and intracranial pressure. Therefore, the progression of intracranial hypertension inevitably leads to a gradual depression of consciousness, which without adequate therapeutic measures becomes a state of soporium and coma.

The development of epileptic syndrome should also be attributed to a certain extent to the category of cerebral brain symptoms and symptom-complex symptoms. According to various data, the onset of this syndrome is observed in 22-30.2% of patients with brain tumors, as a rule, supratentorial localization. More often, the episyndrome is accompanied by the development of astrocytic tumors, and more rarely by meningiomas. In 37% of patients, epipriplets are the debut symptom of a brain tumor.

Therefore, their occurrence without obvious causes at the age of more than 20 years should be considered primarily from the point of view of oncological alertness. As in the case of mental disorders, in the development of the episodrome, not only cerebral pathogenetic mechanisms play a role, but also local (focal) effects of the tumor on the brain tissue. This is especially important when analyzing the causes of development of tumors of the temporal lobe and closely located parts of the brain.

In this case, the formation of an epileptic focus of increased excitability of nerve cells (for example, in the associative regions of the temporal lobe) occurs in the context of the development of focal symptomatology "in the neighborhood". The local component in the formation of epileptic syndrome is also determined by the nature of the aura that precedes the seizure. For example, the so-called motor auras are observed in the development of epileptic syndrome in tumors of the frontal lobe, sensitive hallucinations - for parietal tumors, olfactory, auditory and complex visual - for tumors of the temporal lobe, simple visual - for tumors of the occipital lobe.

The nature of epileptic seizures that occur during the development of a brain tumor varies from small seizures (petit mal) to generalized convulsive seizures (grand mal). An important sign that allows you to connect epileptic seizure with the development of the tumor process is post-ablation loss of function of the motor or speech sphere.

Focal symptomatology arises from the local direct or indirect effect of the tumor on the brain tissue and reflects the violation of certain parts of it (or individual craniocerebral nerves). Primary (direct) focal symptoms that reflect the result of the tumor on the immediate adjacent areas of the brain, as well as secondary focal symptoms, in which the main role is played not so much by the direct mechanical effect of the tumor as by ischemia and swelling-swelling of the surrounding brain tissue. Depending on the degree of remoteness of the secondary symptomatology focus from the tumor node, it is customary to distinguish between the so-called "next door" and "remote" symptoms.

The mechanisms of development of focal symptomatology are different. Thus, primary focal brain tumor symptoms arise due to direct mechanical and chemical effects of the tumor focus on adjacent brain tissue and its ischemia. The degree of severity and duration of such exposure determine the nature of the primary focal symptomatology: first symptoms of irritation or hyperfunction of this area of the brain tissue appear, which are subsequently replaced by symptoms of prolapse.

Symptoms of irritation include Jacksonian and kozhevnikovskie epileptic seizures, decorated and unformed hallucinations, epileptic equivalents, auras. Symptoms of fallout include paresis, paralysis, defects of vision, aphasia, anesthesia.

Occurrence of the symptoms "in the neighborhood" is associated with ischemia of the corresponding areas of the brain due to primary compression, and also due to the mechanical effect of the tumor on the main vessels supplying the blood to the corresponding parts of the brain (for example, stem symptoms in cerebellar tumors, motor aphasia in tumors of the left frontal lobe , defeat of nerves of III and IV pairs in tumors of the temporal lobe).

Symptoms of a brain tumor "at a distance" arise only in the case of a far-gone process, and with the progression of cerebral symptoms can turn into dislocation syndromes. Examples of symptoms "at a distance" is a verbal hallucinosis in tumors of the posterior cranial fossa, symptomatic complexes that occur during the compression of certain parts of the brain during dislocation.

When dislocation of the brain tissue can occur, it is infringed in the anatomical apertures inside the skull or at the exit from it. This situation is designated by the term "wedging" of a particular part of the brain.

[15]

Diagnostics of the brain tumors

Preoperative diagnosis of a brain tumor includes the following components: nosological, topical and pathohistological diagnosis. If there is a suspicion that the patient has a brain tumor, the most common is a general and neurological examination with the formulation of a topical diagnosis. The examination of the neurologist and otoneurologist should be considered concomitant, and if there is a suspicion of the metastatic nature of the oncological process - and other specialists.

Consultation of an ophthalmologist is a prerequisite for the diagnostic process and should include an assessment of visual acuity, determination of visual fields, examination of the fundus. The latter allows revealing indirect signs of increased intracranial pressure in the form of congestive optic discs, their secondary atrophy, and also to determine the presence of primary optic atrophy, which may indicate the localization of the tumor node.

To establish a clinical diagnosis, it is mandatory to involve additional instrumental methods of research, among which the most informative at present are MPT and CT.

These methods, with modern accessibility, make it possible to visualize the tumor center, to estimate its size and anatomo-topographic features, which is the major part of the information necessary for choosing the tactics of surgical treatment. If the information obtained by CT or MRI is insufficient to select treatment tactics, to predict its results, and to improve the quality of surgical intervention, angiography methods are used (it is now considered mandatory in the context of preoperative preparation).

To quickly assess the degree of displacement of the median structures, the method of echoencephalography can be used. Methods such as positron emission tomography (PET), single-photonemission computer tomography (SPECT), electroencephalography (EEG), dopplerography, are used to clarify the diagnosis.

X-ray methods of investigation (primarily craniography) in the diagnosis of brain tumors have now lost a key importance. The classical radiographic signs of the presence of hypertensive syndrome and brain tumors are osteoporosis of the back and tubercle of the Turkish saddle, a posterior inclined process, as well as visualization of a pronounced pattern of finger impressions on the inner surface of the bones of the cranial vault, diffuse reinforcement of diploid veins, expansion and deepening of the pachyon granulation cavities. In early childhood, the presence of intracranial hypertension leads to a divergence of the cranial sutures, a decrease in the thickness of the bones, as well as an increase in the size of its cerebral part.

In addition to X-ray symptoms of hypertensive osteoporosis of bone tissue, in rare cases, osteolysis or hyperostosis can occur in the growth areas of certain types of tumors. Sometimes calcification of tumor sites or displacement of calcified pineal gland is observed.

Methods of SPECT and radioisotope scintigraphy allow to determine the primary focus in case of suspected metastatic nature of the brain tumor, to evaluate some features of tumor biology and, on this basis, to clarify the hypothesis of its possible histological appearance.

Currently, the method of stereotaxic puncture biopsy of a tumor focus is widely used, which allows an accurate histological diagnosis to be made.

In addition to instrumental methods, it is also possible to use a number of laboratory studies, such as determining the hormonal profile (with suspected adenoma of the pituitary gland), virological research.

A fullvolume study (the determination of cerebrospinal pressure, its cytological and biochemical composition) is not at present. Defining and diagnosing a brain tumor, and often performing a lumbar puncture is dangerous because of the threat of development of wedging. Changes in pressure and composition of the cerebrospinal fluid necessarily accompany the development of the tumor process. The pressure of the cerebrospinal fluid and, consequently, intracranial pressure can be increased by 1.5-2 times compared with normal indices.

As a rule, the degree of change in intracranial pressure is somewhat lower than the given interval of extreme upper values. The so-called symptom of protein-cell dissociation, which reflects a significant increase in the concentration of protein in the cerebrospinal fluid at a normal or slightly elevated index of the cellular number, is considered to be classic. This pattern is observed only in the case of intraventricular or close to the ventricular system of the location of the tumor node. A significant increase in cells in the cerebrospinal fluid is observed in malignant neoplasms of the brain with the phenomena of decay of tumor nodes (glioblastoma). In this case, centrifugation of the cerebrospinal fluid allows obtaining a cellular residue in which tumor cells can be detected in 25% of patients. In rare cases with the development of hemorrhage in the tumor, with extensive decay of the tumor node and intensive development of the vasculature of the intraventricular tumor, the cerebrospinal fluid can become xanthochromic.

In the case of identifying clinical signs indicating an increase in intracranial pressure, the dislocation of brain areas, as well as in determining stagnant phenomena on the fundus, the lumbar puncture is strictly contraindicated because of the danger of wedging the cerebellar tonsils into the cervical dural funnel, which inevitably leads to the patient's death.

Peculiarities of diagnosis of metastatic tumors include the use of CT and MRI in contrast mode, stereotactic biopsy of the tumor, radiography (or CT) of chest, bone, CT of the abdominal cavity and pelvic cavity, scintigraphy (spine, pelvis and extremities), mammography women.

[16], [17], [18], [19], [20], [21]

Treatment of the brain tumors

Complex treatment is based on the treatment of brain tumors. Currently, in most cases, surgical, chemotherapeutic and radiotherapeutic methods are used to treat brain tumors.

Under the surgical methods of treatment of brain tumors, the total or partial removal of the mass of tumor cells (actual surgical interventions) or the initiation of acute radiation necrosis of tumor cells (radiosurgical interventions) should now be considered.

Chemo- and radiotherapy methods of influence on the tumor focus lead to a time-consuming death of a certain number of tumor cells, which is of the greatest importance for reducing the population of oncogenic progenitors in the normal brain tissue - peripherally or remotely from a tumor focus.

Surgical treatment of brain tumors includes performing radical operations aimed at maximally complete removal of the tumor, as well as palliative interventions to reduce intracranial pressure and prolong the life of the patient.

By degree of completeness, surgical removal of the tumor can be total, subtotal and partial.

Currently, surgical procedures for the removal of the brain tumor require the use of the latest technological developments and modern equipment, which includes optical magnification systems (operating microscopes), intraoperative neuroimaging systems (intraoperative MRI and CT devices), intraoperative X-ray monitoring systems, stereotactic devices. In a complex, methods of intraoperative visualization allow navigational monitoring of the surgeon's actions in relation to the structures of the brain.

Thermodeasures (laser thermal destruction, cryodestruction) and ultrasonic destruction-aspiration are often used to remove the tumor focus.

Radiosurgical destruction of brain tumors is based on a single targeted irradiation of the tumor node through intact skin using radio-surgical devices - y-Knife, linear accelerator (Linac), Cyber-Knife et al. The total radiation dose of the tumor node is 15-20 Gy. The spatial error in focusing y-rays for y-Knife installation does not exceed 1.5 mm. In this case, the size of the brain tumor should not exceed 3 - 3.5 cm in the maximum diameter. Radiosurgical treatment is mainly subject to metastatic foci in the brain, meningiomas and neurinomas.

Palliative treatment of brain tumors (aimed at reducing the severity of hypertensive and dislocation syndromes):

1. surgical methods for reducing intracranial pressure (among the most effective: external decompression by cranial trepanation, internal decompression by removing a significant part of the bulk tumor or resection of the brain tissue);
2. restoration of normal intracranial pressure and release of the areas of cerebral tissue that are compressed during dislocation (tenotiotomy with temporo-tentorial injection);
3. restoration of the normal liquor flow (liquor-shunting operations: ventriculostomy, ventriculocysternostomy, ventriculoperitetseostomy, ventriculocardiostomy).

Considering the main pathophysiological moments of the development of edema-swelling of the brain tissue in brain tumors, the pathogenetic treatment of these syndromes implies;

1. normalization of external respiration;
2. optimization of systemic arterial pressure;
3. relief of venous outflow from the cranial cavity (the upper half of the body is raised at an angle of 15) and other conservative methods of direct or indirect reduction of intracranial pressure (moderate hyperventilation, craniocerebral hypothermia, osmodiuretics appointment).

Radiation therapy is used for subtotal removal of certain types of brain tumors or in the complex treatment of malignant tumors. There are various types of this treatment: traditional, hyperfractional, photodynamic therapy, brachytherapy, boron-neutron capture therapy.

The total dose of radiation during the course of radiotherapy is up to 60 Gy. The course of radiation therapy is appointed after 2 weeks after removal of the tumor and lasts for 6 weeks. With sessions of daily fractional irradiation with a dose of 180 - 200 mGy. The most radiosensitive brain tumors are: malignant glioma, oligodendroglioma (with subtotal resection or anaplastic variant), dysgerminoma, primary CNS lymphoma, medulloblastoma, ependymoma, meningioma (malignant variants, subtotal or partial removal), pituitary adenoma (after subtotal removal or case of ineffectiveness of drug therapy), chordoma of the base of the skull.

Chemotherapy, depending on the method of administration of the drug may be systemic, regional, intra-arterial (selective), intrathecal and interstitial. An obligatory condition for the course of chemotherapy is preliminary testing of the tumor for sensitivity to the drugs used. The most chemosensitive are such brain tumors as malignant gliomas, primary CNS lymphomas, and tumor infiltrations of the brain membranes.

As perspective methods of treatment of brain tumors, hormone therapy is currently being considered (with the aim of reducing cerebral edema, as well as hormone replacement therapy), immunotherapy (specific, nonspecific, combined, administration of monoclonal antibodies, use of antitumor vaccines, etc.), gene therapy.

Treatment of metastatic brain tumors has its own peculiarities, in the presence of a single metastatic focus, located laterally performing its surgical removal and prescribing a course of radiotherapy. With the medial location of a single focus, the use of radiosurgical treatment and the appointment of a course of radiotherapy are indicated.

In the presence of several foci, among which one large-sized focus is allocated, which gives a clear clinical symptomatology and is located laterally, it is removed and a course of radiotherapy is prescribed. In the presence of three or more foci, the use of a radiosurgical method of treatment and the appointment of a course of radiotherapy to the entire region of the head are indicated. In the lateral location of the foci, surgical removal is possible in this case. In the presence of a large number of foci, the appointment of a course of radiotherapy is indicated.