Brain
Cancer Treatment Generally speaking a brain tumor should be removed as
soon as possible. This removes tissue that does not belong into the brain or the
spinal cord and prevents central herniation. It also removes the possibility of
cancerous degeneration in a benign tumor mass as the tumor ages. The other advantage
is that a smaller tumor is easier to remove in one piece. The neurosurgeon does
not want to take a risk of leaving any cells behind so that the possibility for
a cancer recurrence is much smaller. However, it depends a lot on the location of the tumor, as
sometimes vital structures or major blood vessels are nearby that are in danger
of being damaged with surgery. In the following summary I will briefly touch on
specific therapies for various situations as summarized in Ref. 1,2 and 3. An
entirely different approach is emerging where a vaccine is used for one of the
deadliest bran tumors, glioblasoma multiforme (Ref.5).
Vaccine
For Brain Tumor The deadliest of brain cancers remains GBM
(glioblastoma multiforme), and the prognosis for patients has always been poor.
Progression used to be swift. Surgery followed by radiation and chemotherapy as
the treatment protocol still only offers a life expectancy of about 14 months
for the patient who received the grim diagnosis.
Dr. Amy Heimberger, a neurosurgeon
at MD Anderson Cancer Center in Houston, Texas explains, that the tumor is difficult
to treat, as the cells are different and it is highly invasive. It can be compared
to unscrewing a saltshaker, and there are small tumor particles all over. For
this reason, Dr. Heimberger and the research team think that a vaccination will
be more effective. With a vaccination the immune system is able to recognize these
individual cells, track them, eradicate them or keep them at bay. Other experts
like Dr. Richard Leblanc, director of Mc Gill University's Brain Tumor Program,
agrees. A vaccination avoids the complications of systemic chemotherapy. Initial
results are promising. Patients who had the usual treatment of surgery, radiotherapy
and chemotherapy and the added vaccination lived longer. The median survival was
at least 19 month. The non-vaccinated group only survived for an average of 7.1
months.
In order to optimize the defense of the body, it is still important
to remove as much of the tumor as possible. The current vaccination is not the
only tumor-specific antigen. Researchers will soon be screening tumors to see
what antigen targets they'll be sensitive too. The vaccination can then be selected
accordingly.
The advantage of the current vaccine is that it can be given
"off the shelf". Three injections over a two-week period are needed,
after which monthly boosters will follow.
Malignant
Gliomas This brain cancer requires a combination therapeutic
intervention. First, after the tumor has been spotted on a CT or MRI scan it must
be diagnosed by stereotactic biopsy. The next step is a careful removal of as
much cancer tissue as possible. When the patient has recovered from this surgery,
a full dose of radiotherapy treatment is given. Finally a combination chemotherapy
with nitrosuria is given. Some centers use radioactive seed implants and stereotactic
radiosurgery as an investigative therapy. Unfortunately, none of these therapies
has lead to great survival data. However, without intervention the patient in
the past would have had days or a few weeks to live. Now with the above mentioned
protocols the median survival (50% survival) is about 1 year. 25% of patients
survive 2 years. A better prognosis is achieved with younger than 45 year old
patients, when there is very little or no residual cancer left after the surgery,
or if the pathology report shows "anaplastic astrocytoma" rather than
"glioblastoma multiforme". However, there is a new line of specific
tyrosine kinase inhibitors, which has been shown to be very effective in treating
chronic leukemia(CML) and this medication, called "Gleevec", is now
being studied for glioblastomas (Ref. 4). Meningiomas As
mentioned above, they are benign, but should be removed because of the pressure
they exert onto the healthy structures around them. Also some meningiomas will
degenerate into cancer later on. Medium and large meningiomas can be removed surgically.
However, with very large ones it may be dangerous and technically impossible to
remove the tumor with conventional neurosurgery. Other techniques have been developed
such as stereotactic radiosurgery utilizing the gamma knife or a linear accelerator.
This can only be done at university medical centers. Some of these techniques
are also used for incompletely resected tumors. Low-grade
Gliomas This category would include astrocytomas and oligodendromas.
The recommended therapy for these brain cancers is neurosurgical resection followed
by radiation therapy. The overall prognosis is about 3 to 5 years before a relapse
of the tumor. Ependymomas
This type of cancer is more rare than the others and occurs at the lining of the
passages of the cerebrospinal fluid inside the brain and the spinal canal. Treatment
consists of neurosurgery followed by radiation therapy. The overall survival rate
over 5 years is 50%. If there is no recurrence visible on MRI scans following
the surgery, survival can be more than 70% at 5 years. Medulloblastomas
This type of brain cancer appears in a first peak in the age group of 5 to
9 years. There is a second peak at the age of 20 to 30 years. As this cancer has
a local metastases rate of about 30% at the time of diagnosis the therapy consists
of whole head radiation, spinal cord radiation and radiation to the back part
of the brain where the cerebellum is located. It is there where most medulloblastomas
originate apart from the brain stem adjacent to it. A combination chemotherapy
may have to be used either right away or later for recurrences. The long-term
prognosis with this therapy is about 50% at 5 years and 40% at 10 years. There
are different histological subtypes, with slower dividing cell types being "good
risks" and faster dividing cell types being "poor risks". Shortly
after the surgery the pathologist can tell the treating physician whether a particular
patient would be considered "poor risk" or "good risk". The
poor risk patients have an overall survival rate of 30% at 5 years, whereas the
good risk patients can expect a survival rate of 70% at 5 years. Primary
CNS Lymphomas This is a lymphoma, which originates in lymphatic
tissue of the brain. This disease is dealt with in detail under the lymphoma chapter.
However, it is mentioned here because it has risen very rapidly in the last few
years because of an increase in the number of AIDS patients on the one hand and
patients who had organ transplants on the other hand. In the case of AIDS
patients the immune system is weakened from the AIDS virus. In case of patients
who received organ transplants the anti-rejection drugs are weakening the immune
system. Either way the body cannot fight chromosomal mutations that occur spontaneously
in the B lymphocytes. Before the AIDS epidemic only 1% of all lymphomas originated
in the CNS. Among these 50 % used to be in patients who had received organ transplants.
Now the majority of CNS lymphomas are found in AIDS patients, followed by the
transplant patients. Treatment is by radiation therapy with or without combination
chemotherapy. The prognosis is poor with 1-year survival rates of about
50% and 2-year survival rates of 30%. Pituitary
Tumors These tumors are mostly benign similar to meningiomas.
Like with any other tumor early detection of pituitary tumors is important as
otherwise blindness could result from the direct pressure onto the optic nerve.
These tumors lead to secondary Addison's
disease, which is a deficiency in the pituitary gland hormones. Use
this link to get you there. Acoustic
Neuromas These benign schwannomas originate from the envelope
of the acoustic nerve, which is the hearing nerve. This is a special area for
the ENT(ear/nose/throat) specialist. Usually the ENT specialist diagnosis this
condition and the neurosurgeon either excises it or else organizes stereotactic
radiosurgery for the more complex case. The acoustic nerve comes out of the brainstem
and an acoustic neuroma can occur right at this point, which would be extremely
difficult to approach with conventional neurosurgery, but would be possible to
reach with stereotactic radio- surgery. If the tumor is not removed, the patient
may loose his hearing and ultimately be deaf. |
