Oligodendrogliomas are uncommon Gliomas which account
for approximately 4% of primary Brain tumors. These
tumors arise from Glial cells, called
Oligodendrocytes (the cells that are responsible for
creating and maintaining myelin, which is the
insulating substance around the axons of Brain cell fibre
networks). They are much less common than Astrocytes.
These are tumors of adults, with the peak
incidence being between 35 and 45 years of age.
The initial symptoms of this tumor are not
specific for Oligodendroglioma. Seizures (epilepsy) are
the presenting symptom in 50-80% of cases. Symptoms are more often
related to local mass effect and less commonly to a generalized
increase in Intracranial Pressure (ICP). These symptoms are
similar to those of any intracranial mass lesion and include
headaches, mental status changes, and nausea/dizziness.
Patients presenting with the above symptoms, should have an
evaluation, which includes and MRI or CT scan. Oligodendrogliomas
commonly have some "calcification" within them which can
indicate to the Neurosurgeon that this tumor may include
The initial treatment for Oligodendroglioma is aggressive
removal. The definitive diagnosis is made by microscopic
examination of the tumor tissue taken at the time of surgery.
Aggressive resection of this tumor leads to longer survival,
and results in fewer side effects than "partial debulking"
It is important to recognize that a significant percentage of
Astrocytoma tumors may also have an Oligodendroglioma
component as well. These tumors are called "Mixed
Gliomas". Treatment of a Mixed Glioma is similar to what is
described for an Astrocytoma.
Most Oligodendrogliomas are slow-growing tumors. Tumor grade is
the single most important prognostic variable. Patients with
low-grade lesions have 5- and 10-year survival rates of 74% and
46% respectively; the rates are 41% and 20% for patients with grade
3 or 4 tumors.
Most Oligodendrogliomas respond to some form of chemotherapy.
Newer forms of medication, such as Temodar (temozolamide) and CPT
11, as well as other agents are being used in addition to, or
replacing more conventional drugs such as PCV (procarbazine, CCNU,
and vincristine). Information regarding these
is available on
One of our Neuro-oncologists
generally recommends Radiation Therapy as an adjunct for these
tumors. Benefits of postoperative radiation are somewhat
controversial, since some studies have shown improved survival, while
others have shown no increase in survival.
As in all cases of these "Malignant" tumors, long-term follow-up
Return to Top of Page
This page last edited on 2/19