More work on parsing the American Brain Tumor Association Primer.
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Monday, September 30th, 2002Subendymal Giant Cell Astrocytomas
Monday, September 30th, 2002This section is excerpted from the American Brain Tumor Association Primer on Brain Tumors. The reader is referred to the above link for the Primer in it’s entirety.
“Subependymal Giant Cell Astrocytoma
Subependymal giant cell astrocytomas are ventricular tumors associated with tuberous sclerosis. Please see the section on tuberous sclerosis for additional information.”
Glioblastoma Multiforme
Monday, September 30th, 2002
ABTA primer excerpt Copyright ABTA
“Astrocytoma Grade IV
also called Glioblastoma Multiforme
“Grade IV astrocytoma,” “glioblastoma,” “glioblastoma multiforme,” and “GBM” are all names for the same tumor. Glioblastomas arise from astrocytes – star-shaped cells which form the supportive, glue-like substance of the brain. These tumors represent about 20% of all primary brain tumors and about 50% of astrocytomas. They are more common in older adults, and affect more men than women. Only nine percent of childhood brain tumors are glioblastomas.
Glioblastomas are generally found in the cerebral hemispheres of the brain, but technically can be found anywhere in the brain or spinal cord. Because the glioblastoma is capable of very rapid growth, the first symptoms are usually due to increased pressure in the brain. Headaches, seizures, memory loss, and changes in behavior are the most common presenting symptoms.
Glioblastomas commonly contain a mix of cell types. It is not unusual for the tumor to contain cystic material, calcium deposits, blood vessels, or a mixed grade of cells. Brain tumors, however, are graded based on the most malignant cell found in the tumor, and any astrocytoma that contains necrotic (dead) cells and an extensive network of blood vessels is generally a glioblastoma. The lack of uniformity from end to end of the tumor makes a glioblastoma one of the most difficult brain tumors to treat. While one cell type may be responsive to treatment, other types may be resistant.
The first step in treating a glioblastoma is surgery to remove as much tumor as possible. Radiation therapy almost always follows surgery or biopsy. There are several different forms of radiation therapy – ranging from conventional external beam radiation to stereotactic radiosurgery to conformal radiation therapy – which might be suggested. Other types of radiation therapy, such as implanted liquid radiation or monoclonal antibodies tagged with radioactive particles, may also be considered.
Chemotherapy might be given before, during or after radiation. The most commonly used drugs for adults are BCNU, CCNU, procarbazine, and temozolomide. Biodegradeable wafers containing BCNU may be placed in the cavity created by tumor removal. Other new delivery systems are under investigation. Chemotherapy might also be used in children under the age of three to delay radiation.
Antisense therapies block the messages given off by malignant cells, altering their ability to interfere with the normal growth of surrounding cells. Protease inhibitors, such as marimastat and tamoxifen, block the ability of tumor cells to make the proteins needed for tumor cell reproduction. Angiogenesis inhibitors may be capable of interupting the blood supply to a tumor, thus controlling tumor growth.
Immunotherapy is the use of the body’s own immune system to fight a tumor. There are several research studies focusing on this area of treatment, and many of the programs are open to those with a glioblastoma. Immunotoxins, such as diptheria or pseudomonas, link a toxin to an antibody and carry it to the tumor cells. Interferons are thought to inhibit tumor cell growth by stimulating the immune system; they may also be angiogenesis inhibitors. Other researchers are using gene therapies as a way of controlling tumor growth. In one method, specially-engineered genes make tumor cells more susceptible to drug therapy. In another method, gene therapy is used to stimulate the body’s natural production of immune substances. Gene therapy may also be used to restore the normal function of tumor suppressing genes within tumor cells.
Recurrent tumors can be treated with additional surgery, another form of focused radiation, chemotherapy, or any number of experimental approaches as mentioned above. “
Anaplastic Astrocytomas
Monday, September 30th, 2002
ABTA primer excerpt Copyright ABTA
Anaplastic Astrocytoma
also called Malignant Astrocytoma or Grade III Astrocytoma
An anaplastic astrocytoma is a grade III tumor. Astrocytomas often contain a mix of cells and cell grades, but brain tumors are graded by the highest grade (most abnormal) cell seen in the tumor. These tumors tend to have tentacle-like projections that grow into surrounding tissue, making them difficult to completely remove during surgery. The word “anaplastic” means malignant, and because of this, treatment for an anaplastic astrocytoma may be more aggressive than treatment for a lower grade tumor.
The treatment options your doctor outlines will be based on the size and location of the tumor, what it looked like under the microscope, if and how far the tumor has spread, any previous treatment, and your general health. Generally, the first step in the treatment of anaplastic astrocytomas is surgery. The goals of surgery are to obtain tumor tissue for diagnosis and treatment planning, to remove as much tumor as possible, and to reduce the symptoms caused by the presence of the tumor. There are some circumstances, such as certain medical conditions or concerns about the location of the tumor, in which a biopsy may be done in place of surgery. The tissue obtained during the biopsy is then used to confirm the diagnosis.
Because the tentacle-like cells of an astrocytoma grow into the surrounding tissue, these tumors cannot be totally removed during surgery. Partial removal can help decrease symptoms; the tissue obtained during that surgery confirms the type of tumor. Radiation is then used to treat the remaining tumor. There are several forms of radiation therapy available – conventional external beam radiation, focused radiation or stereotactic radiosurgery, implanted radiation, or conformal radiation. Your radiation oncologist will determine which is best for your particular tumor.
Some treatment plans include the use of chemotherapy for anaplastic astrocytoma. BCNU, CCNU, procarbazine, cisplatin, and temozolomide are commonly used drugs. Some clinicians recommend the use of chemotherapy prior to radiation; in these circumstances the chemotherapy may reduce the amount of tumor to be treated, and may serve as a radiation sensitizer. Other treatment plans may call for the implantation of biodegradable wafers containing BCNU into the cavity created during tumor removal. Still other physicians choose not to use chemotherapy for the initial tumor, “reserving” it for re-growth if necessary.
New drugs, new drug combinations, and new ways of delivering those drugs are being studied; these treatments are offered in organized research programs called clinical trials. Many clinical trials are available for anaplastic astrocytomas – both as initial treatment and as treatment for a recurrent tumor. Many of those clinical trials can be found through the Cancer Information Service at 800-422-6237.
Anaplastic astrocytomas tend to recur, and when they do, they may regrow as a higher grade tumor. Treatment is based on the grade of tumor at recurrence.
Low Grade Astrocytomas
Monday, September 30th, 2002
ABTA primer excerpt Copyright ABTA
“Diffuse Astrocytoma
also called Astrocytoma, Low Grade or Astrocytoma Grade II
(types: Fibrillary, Gemistocytic, Protoplasmic Astrocytoma)
These low grade astrocytomas tend to be infiltrating tumors, capable of growing into surrounding tissue, but tumors which grow relatively slowly.
These astrocytomas are grouped by the appearance and behavior of the cells for which they are named. For example, the nuclei of Fibrillary astrocytoma cells are cigar-shaped; this type of astrocytoma tends to contain microcysts and mucous-like fluid. Protoplasmic astrocytoma nuclei are round or oval in shape. These tumors also tend to contain microcysts and mucous-like fluid. Gemistocytic astrocytomas are plump, glassy, angular shaped cells. (Until recently there had been some disagreement as to the grade of the gemistocytic astrocytoma. Some pathologists considered this to be a grade III tumor since the gemistocytic astrocytoma, in particular, tends to recur as an anaplastic astrocytoma. The WHO classification system published in 2000 defines these as grade II tumors.)
Regardless of the cellular appearance of these grade II astrocytomas, surgical removal may be suggested for accessible tumors (tumors that may be removed without causing undue neurological damage). If “total” surgical removal can be achieved, periodic follow-up with MRI or CT scans might be the only additional care required. It is important to realize that “total” removal generally means removal of all of the tumor visible to the neurosurgeon’s eye. Microscopic cells, too small to see, can remain behind or may have spread to nearby tissue. Those cells may later begin to re-grow. However, even with incomplete removal these tumors tend to grow very slowly, and it may be several years before symptoms reappear due to tumor regrowth.
In adults and older children, radiation therapy may be suggested in addition to surgery, or radiation may be used to treat a low grade astrocytoma which is unable to be removed. The role of chemotherapy in treating these tumors is under investigation. Further treatment might be recommended only if the tumor recurs. Children younger than three might receive chemotherapy so that radiation can be delayed.
These low grade tumors may recur as a higher grade tumor; thus, periodic follow-up and attention to the return of symptoms is important. Treatment of the recurrent tumor would be based on the tumor’s grade at the time of re-growth.”
ABTA Primer-Pilocytic Astrocytoma
Sunday, September 29th, 2002ABTA primer excerpt Copyright ABTA
“Pilocytic Astrocytoma
also called Juvenile Pilocytic Astrocytoma
These grade I astrocytomas are usually non-infiltrating tumors, meaning they tend to stay in the area in which they started and do not spread into surrounding tissue. They generally form cysts, or may be enclosed within a cyst. Invasion (growth into surrounding areas of the brain or spinal cord) is rare. Although these are usually slow growing tumors, they can become very large.
Pilocytic astrocytomas are the most common glioma in children. They are generally diagnosed in children and young adults under the age of 20, and are rarely seen in older adults. They are the most benign tumor of the astrocytomas. Many optic gliomas and cerebellar astrocytomas are pilocytic astrocytomas.
Pilocytic astrocytomas are generally considered “benign” tumors and are often cured by surgery alone. In adults and older children, radiation therapy might follow surgery if the tumor cannot be completely removed, or the residual tumor may be carefully watched. In a “watchful waiting” situation follow-up MRI scans are done at regular intervals to monitor for possible re-growth. If the tumor recurs, re-operation and some form of radiation are options. Some pilocytic tumors, such as most optic gliomas, cannot be safely removed because of their location and initial treatment may involve observation only.
The term “anaplastic” or “malignant” pilocytic astrocytoma is used only when the tumor has developed an extensive blood supply around the tumor, or the tumor contains dead cells called necrosis. These rare tumors require more aggressive treatment than a benign pilocytic astrocytoma”
Desmoplastic Infantile Astrocytoma
Sunday, September 29th, 2002
ABTA primer excerpt Copyright ABTA
“Desmoplastic Infantile Astrocytoma (DIA)
DIAs are very rare grade I astrocytomas. These large, cystic tumors are usually diagnosed in infants under the age of two, although in some circumstances they have been seen in children and young adults. They tend to arise in the supratentorium – the area above the membrane that separates the cerebral hemispheres from the posterior fossa of the brain. It is not uncommon for these tumors to grow quite large and spread through more than one lobe of the brain. Symptoms usually include an increase in the size of the bay’s head, hard and bulging fontanelles (the “soft spots” of the infant’s skull), and eyes that focus downward. Seizures, hyperactive reflexes, and a palsy of the sixth and seventh nerve may also be seen.
Skull xrays may show changes in the bone near the tumor, and a large mass is commonly seen on MRI. Despite the size of these tumors and the young patient age, surgical removal of all visible tumor often results in long term tumor control.”
It Worked!
Sunday, September 29th, 2002
More work on parsing the American Brain Tumor Association Primer.
ABTA Attribution
Sunday, September 29th, 2002This section is excerpted from the American Brain Tumor Association Primer on Brain Tumors. The reader is referred to the above link for the Primer in it’s entirety. The local Primer table of contents can be found here.
ABTA-Cerebellar Astrocytomas
Sunday, September 29th, 2002ABTA primer excerpt Copyright ABTA
Cerebellar Astrocytoma
“Cerebellar astrocytomas” are astrocytomas found in the cerebellum – the lower, back part of the brain which controls balance. More than 80% of cerebellar astrocytomas are grade I, localized, cystic (fluid filled) tumors although higher grades of tumor do occur. Malignant cerebellar astrocytomas and spread of this type of tumor are rare. The cerebellar location is more common in children than adults and is usually very accessible to the neurosurgeon.
Surgery is the primary treatment and if “total” removal is possible – meaning that all tumor visible to the surgeon’s eye is able to be removed – additional therapy might not be needed. In adults and older children, radiation might be recommended for an incompletely removed or a higher-grade tumor. Further treatment might be needed only if the tumor recurs. For children under three, chemotherapy may be used to delay the use of radiation therapy until the brain has further matured.
If the tumor recurs, a second surgery, radiation, or chemotherapy can be considered.