The term astrocytoma refers to a type of central nervous system tumors belonging to the glioma family, i.e. primary brain tumors that originate from tissue called glial. Specifically, astrocytomas originate from astrocytes, a type of star-shaped glial cells that have the function of nourishing and supporting nerve cells, neurons. Usually, astrocytomas form in areas of the brain called the telencephalon, cerebellum, and brainstem. Only in very rare cases can they develop from an astrocyte located in the spinal cord. Among gliomas, astrocytoma is the most common tumor and covers about one third of all primary brain tumors, ie those not caused by metastases from different tumors located in other parts of the body. They are the most frequent tumors in pediatric age, as they represent about 25% of all cancers that affect children. In these tumors the border with healthy brain tissue is very blurred, there is no clear limit and cancer cells can be found even at a distance from the lesion principal.Symptoms
The disorders (symptoms) associated with the presence of an astrocytoma can be varied and deceptive. The main factors that can influence its appearance and variety are the location of the tumor, its size and how fast it grows.
If the astrocytoma is localized in the frontal lobe of the brain, the following appear:
- sudden or gradual changes in mood and personality
- weakness or numbness in either side of the body
Localization in the temporal lobe causes:
- speech problems
- memory problems
- coordination problems
Finally, if the astrocytoma is localized in the parietal lobe of the brain, the following can occur:
- problems with writing
- weakness or numbness in either side of the body
There are also some signs and disorders common to many forms of astrocytoma, such as:
- headache (headache), often worse in the morning
- nausea and vomit, especially in the morning
- poor eyesight, such as clouding, double vision (diplopia), loss of visual acuity (visus)
In the forms of astrocytoma with a low degree of malignancy (grade I and II), the following may also appear:
- loss of strength
- decreased sensation of one side or part of the body (hemiparesis)
- memory problems
- cognitive problems, of reasoning, of memory, of language
- mood changes and personality change
In the forms with a higher degree of malignancy (III and IV degree) the first complaints, in particular headache (cephalea), refer to the increase in pressure inside the skull.Causes
As with most cancers, the causes of the development of an astrocytoma are still unknown. The role played by chromosomal and genetic mutations in the uncontrolled growth of the cells involved, in this case those of the brain, is known. of known environmental risk that can increase the likelihood of an astrocytoma is exposure to high doses of ionizing radiation. For this reason, for example, people undergoing radiotherapy for the treatment of cancer, have an increased risk of develop a glioma even after many years, the group to which the astrocytoma belongs. Family history - the presence of one or more cases of glioma in the same family - can also increase the risk of developing the disease, albeit modestly. The same thing can be said for some rare inherited syndromes such as Lynch syndrome, Cowden syndrome, Li-Fraumeni syndrome, Turcot syndrome and type I and II neurofibromatosis.
However, it is important to remember that exposure to a risk factor does not mean that the disease will certainly develop sooner or later.Diagnosis
In the presence of disorders associated with astrocytoma, where they are not attributable to other more common diseases, it is advisable to contact your doctor to carry out further investigations that include:
- thorough medical examination, to understand the type of disease that determines the disorders and signs present
- examination of tendon reflexes, with the aim of verifying the presence or absence of neuromuscular and coordination disorders
- eye test, which allows the doctor to observe the optic nerve and evaluate its involvement
- mental status assessment, and the skills of reasoning, language and memory, in order to understand which area of the brain may be involved
Subsequently, to be sure of the presence of the tumor and to know its exact location, the doctor will prescribe more in-depth instrumental investigations such as nuclear magnetic resonance imaging (MRI) and computed tomography (CT). The astrocytoma is better highlighted by MRI. Investigations are usually performed after intravenous infusion of a contrast medium which allows for better evaluation of tumor activity based on the amount of substance absorbed.
Neuroradiological diagnosis, however, is not always 100% decisive and it may be necessary to perform a brain biopsy. In this case, to perform the removal of tumor tissue fragments from the brain, a " helmet ”which makes possible a three-dimensional processing of the images. This visualization is essential to accurately guide the needle which is inserted into a small hole created in the skull under general anesthesia (stereotaxic technique). The tissue fragments taken are subsequently analyzed under a microscope.
On the basis of the histological characteristics and, consequently, of the therapies to be performed, four degrees of malignancy are distinguished: grades I and II indicate low malignancy, while grades III and IV have a high degree of malignancy.
Low-grade malignancy astrocytomas
This group includes:
- astrocytomapilocytic, grade I, characterized by slow growth and with little tendency to evolve into more malignant forms. It represents the most frequent form of glioma in children, with cure rates greater than 90% with surgical excision alone, when complete. In children, the most common site is the cerebellum. It can also occur in young adults, usually under the age of twenty. Although it is a grade I form, poorly infiltrating and with a good life expectancy, it can still evolve into more malignant forms
- diffuse astrocytomas, second-degree tumors which generally arise between thirty and forty years of age. They rarely affect children. They can evolve very slowly and allow for a very long survival. After an average period of about 5 years, they can develop into more aggressive forms. The fibrillar, gemistocytic and protoplasmic astrocytoma belong to this group
In low-grade astrocytomas, the difference between cancer cells and healthy cells is less marked and the boundary with healthy tissue is less evident. It is for this reason that they respond poorly to surgical, drug or radiation therapy. Surgical removal is possible only in cases of small tumors that are in an area where the use of surgery cannot cause damage such as, for example, speech difficulties, paralysis or other.
Astrocytomas with a high degree of malignancy
This group includes:
- anaplastic astrocytoma, grade III, a highly malignant tumor, called anaplastic because the astrocytes of the tumor mass lose their typical appearance and take on the characteristics of undifferentiated (anaplastic) cells. This type of cancer accounts for about one third of all astrocytomas and can appear at any age, but is more common in older people, peaking between 50-60 years of age. Compared to low-grade astrocytomas, it grows faster, tends to reform more often and more quickly, and infiltrates the surrounding healthy tissue making it difficult to completely remove it surgically. Life expectancy is negative with a two-year survival of 50%, a 5-year survival of 18%
- glioblastoma multiforme, grade IV, is the most feared brain tumor due to its aggressiveness and invasiveness. It has a rapid growth and, above all, a high tendency to recur. It accounts for about 30% of all brain tumors and about 50% of all astrocytomas. It usually affects people over the age of 50. The average survival is around the age of 50. 12 months, while the two-year one is 10%
Numerous factors influence the therapeutic choices in the case of an astrocytoma: the degree of malignancy, the location, size and rate of growth of the tumor mass. The therapeutic possibilities in the case of an astrocytoma are essentially three: surgery, radiotherapy, chemotherapy.
Whenever possible, regardless of the degree of malignancy, surgical removal is best.
Surgical treatment aims to remove all of the tumor or, if this is not possible, most of the tumor mass. It can only be performed if the tumor is localized and does not affect an "area of the brain where the surgery would cause impairments to the person." Surgical removal has the advantage of reducing compression on the remaining healthy brain tissue and increasing the effectiveness of subsequent therapies by removing the hemorrhagic and necrotic areas. Any tumors that cannot be surgically removed can be subjected to stereotaxic biopsy in order to determine the exact type of tumor. The surgery is delicate and dangerous, and for this reason the doctor, together with his staff, is required to inform the patient of the possible risks of the procedure.
Radiotherapy is based on the use of high-energy ionizing radiation and has the aim of destroying cancer cells. In the case of astrocytomas it is performed in two very different situations:
- Grade II or higher astrocytomas, after surgery
- inability to perform the surgery, in this case radiotherapy represents the main and most important therapeutic treatment
Radiation therapy is performed in a "day hospital" for a period of approximately two months.
Chemotherapy is the administration of drugs capable of killing all rapidly growing cells, including cancer cells. It is prescribed by doctors when they believe the risk of a relapse (relapse) is very high or when there is a suspicion that some cancer cells may be present in other tissues of the body (metastasis). Such situations are more likely in the case of grade III and IV astrocytomas. Chemotherapy essentially uses temozolomide, carmustine and cisplatin, drugs that cross the blood brain barrier more easily than others.
If the astrocytoma causes edema around the tumor area, a therapy based on corticosteroid drugs that reduce inflammation may be prescribed.
After the surgical removal of the tumor mass and during any radiotherapy and chemotherapy treatments, the person must also undergo a physiotherapeutic rehabilitation which aims to recover, at least in part, the neurological faculties that the presence of the tumor, or the intervention itself can have damaged.
Life expectancy depends mainly on three factors:
- degree of astrocytoma, a person with Grade I astrocytoma has a good chance of making a full recovery after surgical removal. In contrast, people with grade IV astrocytoma, even after surgery, have an average life expectancy of just over 30 weeks.
- location of the tumor mass, if the tumor is located in a hard-to-reach place and therefore is not operable, a drastic reduction in the survival rate is observed, since radiotherapy and chemotherapy are not as effective
- quick assessment, the later the cancer is found, especially if it is advanced, the less likely it is to recover
Bambino Gesù Pediatric Hospital. Glioma, astrocytoma