Generality
When we talk about brain cancer, we are referring to the growth of an abnormal mass of cells within the brain. To cause this unusual cell formation is a genetic mutation of DNA.
The symptoms of a brain tumor are numerous and depend mainly on three factors: location, size and severity (growth rate) of the neoplasm. A common symptom in many brain tumors is headache.
There are several therapeutic treatments; their choice and also their effectiveness depend on the characteristics (location, severity and size) of the neoplasm.
Brief reference to Genetic Concepts
Before describing brain cancer, it is useful to make a brief reference to some key concepts.
What is DNA? It is the genetic heritage of an individual, a sort of biological code in which the physical features, predispositions, physical qualities, character, etc. of a living organism are written. The DNA is contained in all the cells of the body having a nucleus, as it is inside it.
What are chromosomes? According to the definition, chromosomes are the structural units in which DNA is organized. The human cells contain, in their nucleus, 23 pairs of homologous chromosomes (therefore, 46 chromosomes in all); each pair is different from another, as it has a specific gene sequence.
What are genes? They are short stretches, or sequences, of DNA with a fundamental biological meaning: from them, in fact, proteins are derived, that is, fundamental biological molecules for life. In genes, there is "written" part of what we are and what we will become.
What is a genetic mutation? It is a mistake within the DNA sequence that forms a gene. Because of this error, the resulting protein is defective or completely absent. In both cases, the effects can be deleterious both for the life of the cell, in which the mutation occurs, and for that of the organism in its totality. Congenital diseases and neoplasms (or tumors) are responsible for one or more genetic mutations.
What is a brain tumor?
A brain tumor is a mass of cells, formed and increased in a completely anomalous way inside the brain.
THE DIFFERENT TYPES OF BRAIN TUMORS
Brain tumors, or brain tumors, are classified according to various criteria, such as the site where the growth of the tumor mass begins and the rate of diffusion (invasiveness) of the latter.
- The point of origin of the tumor mass: primary tumor and secondary (or metastatic) tumor .
One speaks of a primary brain tumor when it arises spontaneously in the brain or in a neighboring anatomical region (for example, the meninges or the pituitary gland); we talk instead about secondary brain tumor, when the mass of cells derives from another neoplasm located in a part of the body distant from the brain (for example, in the lungs).
- Growth rate: benign tumor and malignant tumor .
When the growth and spread of the tumor are slow, we speak of a benign brain tumor; vice versa, when the growth and the formation of the anomalous mass are fast, we speak of malignant brain tumor (or carcinoma).
A FURTHER DISTINCTION: DEGREES OF A BRAIN CANCER
Figure: a brain tumor (marked by arrows and white asterisks).
Next to the two previous criteria of distinction, there is a third that classifies brain tumors on the basis of 4 degrees (I to IV).
The first two grades, I and II, are characterized by slow and limited tumor growth in a brain area.
Grades III and IV, on the other hand, are distinguished by a rapidly growing and highly invasive mass.
In light of what has been said so far, it could be argued that grade I and II brain tumors are benign, while those of grade III and IV are malignant. However, the aforementioned statement omits a very important aspect that can occur, namely the possibility that a benign tumor of grade I or II evolves into a malignant tumor. This is what happens, for example, for gliomas .
Benign brain tumors :
| Malignant brain tumors
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Epidemiology
Brain tumors can occur at any age. However, the most affected individuals are the elderly (although it should be noted that there are brain tumors typical of childhood).
According to a British statistic, concerning the United Kingdom, every year 4, 300 benign brain tumors are diagnosed, most of which are gliomas, and 5, 000 malignant tumors, mainly secondary.
Primary tumors are less common than secondary ones.
Causes
To cause a brain tumor (both primary and secondary) is a genetic mutation, such that the cells, affected by this error, grow and divide at a higher rate than normal.
WHAT INCREASES THE RISK OF A MUTATION?
After extensive research and statistics, some factors have been identified that increase the possibility of developing a brain tumor.
The first factor is advanced age : elderly people, in fact, are definitely the most affected subjects, although some brain neoplasms are exclusive to childhood.
The second factor is represented by a series of congenital diseases, which predispose to the growth of a tumor mass within the brain.
Congenital conditions favoring a brain tumor:
- Neurofibromatosis
- Tuberous sclerosis
- Turcot syndrome
- Li-Fraumeni syndrome
- Von Hippel-Lindau syndrome
- Gorlin syndrome
The third factor is related to ionizing radiation, especially when used for the treatment of a previous tumor. In fact, it is unfortunately the fact that the exposure, for therapeutic reasons, to ionizing radiations favors the onset of other neoplasms.
The fourth factor concerns the family history of an individual. If there have been previous cases of brain cancer in the family, then it is easier for the disorder to affect even close relatives.
PRIMARY BRAIN TUMORS
Genetic mutations, which cause primary brain tumors, can arise in different types of brain cells. Depending on the place of origin, the following neoplasms develop:
- Astrocytoma
- ependymoma
- Oligodendrogliomas
- Germ cell tumor
- Medulloblastoma
- Meningioma
- Acoustic neurinoma
- pineoblastoma
NB: astrocytoma, ependymoma and oligodendroglioma belong, more generally, to the category of gliomas.
SECONDARY BRAIN TUMORS
As anticipated, secondary brain tumors derive from tumors arising elsewhere in the rest of the body, again due to a genetic mutation. This dissemination process is also known as metastasis or metastasis . The most common neoplasms that cause metastases in the brain are: breast cancer, colon cancer, kidney cancer, lung cancer and, finally, melanoma.
Symptoms and Complications
The symptoms of a brain tumor are quite varied and depend on the size, location and rate of cell mass growth .
A benign brain tumor, having a decidedly lower rate of growth than a malignant tumor, manifests itself in a less evident, sometimes just mentioned way.
A tumor at the level of the frontal lobe of the brain (ie in the anterior part) causes a sense of weakness, changes in personality and loss of smell, while a tumor at the level of the occipital lobe (ie in the posterior part) causes a loss of sight.
GENERAL SYMPTOMATIC FRAMEWORK
Due to the close anatomical proximity between brain and skull, a brain tumor in growth phase fails to expand as it could, consequently it merely pushes against the walls of the bone lining and against adjacent areas.
This pressure, known as intracranial pressure, is the main cause of headache (the most characteristic symptom of brain neoplasms) and other manifestations, such as:
- Nausea and vomiting, without reason
- Eyesight problems: blurred or double vision and loss of peripheral vision
- Attacks of epilepsy
- Confusion during everyday chores
- Difficulty maintaining balance
- Gradual loss of sensitivity or movement of the legs or arms
- Difficulty in expressing oneself in words
- Sudden changes in personality and behavior
- Hearing problems
The aforementioned list does not represent what is regularly observed every time a brain tumor appears, but only a general picture of the possible symptoms. In fact, an individual tends to lose especially the brain functions controlled by the area of brain in which the tumor mass grows.
Figure: brain tumor is characterized by frequent headaches, which arise without apparent reason.
HEADACHE: WHEN TO REFER TO THE DOCTOR?
Suspicious headaches are those that arise without any explanation and that become, with time, more and more frequent and severe.
Diagnosis
To diagnose a brain tumor, proceed as follows.
First of all, we start with a neurological examination ; after that, instrumental tests are needed, such as MRI or CT, to understand the precise location of the tumor and what may have originated.
Finally, through a brain biopsy, the malignant or benign nature of the neoplasm is determined.
NEUROLOGICAL EXAMINATION
The doctor submits the patient, who complains of the symptoms of a brain tumor, to various controls, aimed at evaluating their sight, hearing, balance, coordination and reflexes. The partial or total loss of one of these abilities can already provide valid information regarding the area of the affected brain.
INSTRUMENTAL TESTS
The instrumental examinations serve to clarify both the precise location of the tumor and whether the tumor is primary or secondary.
Figure: this is how a brain tumor (marked by the red arrow) appears in a nuclear magnetic resonance.
Nuclear magnetic resonance ( NMR ) is the examination of choice, but computed tomography ( CT ) and positron emission tomography ( PET ) play an equally important diagnostic role.
Know where the tumor mass is formed and whether this is, or not, the result of metastasis helps to plan the therapy correctly.
BEREBRAL BIOPSY
The brain biopsy takes place after identifying the area affected by the tumor; the examination consists in taking a small portion of the neoplastic mass and in its observation under a microscope.
The characteristics of tumor cells clarify the benign or malignant nature of the neoplasm.
Treatment
Curing a brain tumor is possible. To do this, the choice of the most appropriate therapy depends on the following factors:
- Type, location and size of the tumor
- State of health of the patient
Possible treatments include surgical removal, radiotherapy, chemotherapy, radiosurgery and targeted therapy . Such interventions are not mutually exclusive, indeed, very often, to ensure a better cure, they opt for their association (for example, surgical removal followed by sessions of radiotherapy and / or chemotherapy).
Once the treatment is over, we move on to rehabilitation therapy .
Surgical removal
The conditions
Surgical removal is a delicate operation, which is practiced only when it is possible to access the brain area occupied by the tumor without a hitch. If these conditions exist, the operation is performed under general anesthesia .
The procedure
After having engraved the head and the skull of the patient ( craniotomy ) at the point corresponding to the site of the neoplasm, the neurosurgeon removes the tumor mass, taking care not to damage the healthy parts of the brain. The success of the operation depends on how large and infiltrated the tumor: in the most complicated cases, the result is partial, therefore it is necessary to associate one or more of the other treatments mentioned above (radiotherapy, chemotherapy, etc.).
The complications
The risks of the operation consist of: infections, cerebral haemorrhages and lesions of the nerve endings.
Radiotherapy
Radiation therapy involves subjecting the patient to various cycles of ionizing radiation (high energy X-rays), in order to destroy the tumor cells.
The procedure can be performed either through an external radiation source, which acts on a large area of the head, or through an internal source, placed in the immediate vicinity of the area affected by the tumor ( brachytherapy ).
In general, one opts for the external source in the case of secondary tumors, since, in these situations, the neoplasm is more widespread; on the contrary, an internal source is chosen when the tumor is primary and localized in a precise area.
fatigue, headache, irritation and increased risk of developing other cancers. The onset of these depends, above all, on the doses of radiation received.
Chemotherapy
Chemotherapy consists of the administration of drugs capable of killing all rapidly growing cells, including cancer ones.
These preparations, the choice of which usually depends on the type of tumor in question, can be taken by mouth or intravenously.
The most widely used chemotherapy drug is temozolomide .
The side effects depend on the doses of drug taken and consist of: nausea, vomiting and hair loss.
Chemotherapy and surgery
During the surgical removal procedure, it is possible to place, near where the tumor mass was, a thin bar (called with the English word wafer ) containing a chemiterapic drug. In the days following the surgery, this wafer slowly releases its contents, acting directly against cells with tumor characteristics that have not been removed with surgery.
Radiosurgery
Radiosurgery is an operation performed only in a few hospital centers and requires very sophisticated instrumentation.
Briefly, it consists in striking, with a very intense beam of ionizing radiation, the area occupied by the tumor, when it is located in an inaccessible point for surgical removal.
The treatment usually takes place in a single session.
Targeted Therapy
There is talk of targeted therapy when drugs are given that can act exclusively against cancer cells. Unlike chemotherapy (in which some healthy cells can also be destroyed), the target of targeted therapy is a molecule or process characteristic of the cancer cell.
For example, in the case of some malignant gliomas, bevacizumab (or Avastin ) is administered, which blocks a fundamental neoplastic mechanism, such as the formation of new blood vessels.
Rehabilitation Therapy
Rehabilitation aims to restore the capacity lost following brain cancer. Depending on the area of the brain affected, it may be necessary:
- Physiotherapy : to restore motor skills.
- Occupational therapy : to make the patient independent again, during daily activities, work, school, etc.
- Language therapy : to restore spoken language.
Prognosis
Every patient with a brain tumor has its own prognosis, which depends on numerous factors, such as:
- Location, size and type of cancer. A primary tumor, perhaps benign and located in a region accessible to the surgeon, is more easily treated than an extended tumor and placed in inaccessible brain areas. The secondary brain tumors are, by far, the most serious and those characterized by the worst prognosis.
- Early diagnosis. Identifying a brain tumor in the early stages allows a less invasive therapeutic treatment, with a reduced risk of complications.
- State of general health of the sick individual. An individual who is not in perfect health conditions is less susceptible to radiotherapy, surgery, chemotherapy, etc. It is up to the medical staff to determine which treatments are most appropriate.
- Quality of therapy. Unfortunately, some brain tumors are so severe that they require massive and highly invasive therapies. In these cases, it may be useful to rely on a neurosurgeon and an oncologist who are experts in the field, although it should be pointed out that certain characteristics can make brain cancer difficult to cure.
