Sara: I do not have any oncology
expertise, but I have talked to a few experts and done some reading. My notes
might help Barbara's friends understand better the tumor.
Brain tumors almost always involve the glia. These are non-neuronal
brain cells. These cells surround neurons (in a one to one ratio overall, and 3 to 2 ratio in gray matter) and hold them in place, providing support
and protection. They also supply nutrients and oxygen, form myelin for
insulation, and destroy pathogens.
Most of the glial cells are astrocytes (or astroglia), star-shaped cells.
They anchor neurons to their blood supply and regulate the extracellular
chemical environment (remove excess ions, recycle neurotrasnsmitters).
Astrocytomas are the most common form of glioma (brain tumor involving
the glia). They can occur in most parts of the brain, but are most
commonly found in the cerebrum, and they are more common in adults than
in young people. A grade 3 astrocytoma is also called 'anaplastic
astrocytoma'. The grade is an indication of how rapidly the tumor is
growing. They look at how many cells are actually dividing and whether
there are new blood vessels; both of these are indicators of tumor growth.
There might be necrosis (dead tissue), an indication that the tumor is
outgrowing its blood supply.
There are three standard types of treatment for high-grade gliomas: surgery,
radiation therapy, and chemotherapy. Because grade 3 and 4 tumors have a
tendency to grow rapidly, treatment must be started soon after surgery, as
soon as the surgical incision has healed (usually 2 to 4 weeks after surgery).
These therapies are helpful, but they do not cure high grade gliomas: the
tumor cells infiltrate into surrounding brain and most glioma cells are
partially resistant to radiation and chemotherapy.
High-grade glioma cells almost always start to grow again at some point in time. The treatment aims at delaying this regrowth as long as possible.
Regrowth does not necessarily imply loss of control of the tumor, but it
does mean that a new series of treatments should be considered.
Whether surgery is possible depends on the location of the tumor. There
are areas where surgery is too risky. When a tumor is located in a sensitive area of the brain, the neurosurgeon will perform a biopsy with a small needle, to avoid damage to brain function.
Radiation treatments are the standard. The traditional form is called `fractionated radiation' - the delivefy is in small doses, or fractions.
The doses are given five days a week, Monday through Friday, for 4 to 6
weeks. Each treatment takes only a few minutes, and there are no immediate
side effects during each treatment. As the treatment progresses, there
will be hair loss in the area where the radiation beam passes into the
tumor. Most patients experience fatigue by the second or third week; a
30 minute nap every afternoon is helpful. Long-term effects of the radiotion
therapy depend on the dosage; it is best to discuss this with the radiation
oncologist.
This type of radiation is called `external beam radiation': the radiation
is delivered from outside the body. It allows for a wider area to be treated. There is a more precise type of radiation therapy called `fractionalized stereotactic radiotehrapy', which minimizes damage to
healthy tissue. Ask the radiation oncologist which approach he recommends
and why.
Most patients feel better during radiation therapy if they take a small dose of a steroid which reduces brain swelling (Decadron, also called
dexamethasone). This drug has many side effects, but these are usually less important that the benefit from taking it; it is important to find the smallest dose that is helpful.
Chemotherapy might not be necessary as a reinforcement to radiation; the
doctors might decide not to use it now, but it might be necessary later
on, as the tumor regrows.
