Learn all about oligodendroglioma grades and treatment for brain cancer. Glioma is a general term for a group of tumors that start in the supportive tissues (glial cells) of the brain or spinal cord. They are the most common type of primary brain tumors in adults and account for about 70% of all malignant (high-grade) tumors of the central nervous system (CNS).
Oligodendrogliomas belong to a group of tumors called gliomas. Different types of gliomas are named after the different types of glial cells. Oligodendroglioma is a glioma that develops from a type of glial cell called an oligodendrocyte. These cells make up the fatty covering of nerve cells. Oligodendrogliomas usually start in the brain, or sometimes in the spinal cord. They can sometimes spread from where they started to other parts of the brain or spinal cord. They don’t spread to other parts of the body.
About 4% of primary brain tumors are oligodendrogliomas, representing about 10-15% of the gliomas. Only 6% of these tumors are found in infants and children. Most oligodendrogliomas occur in adults ages 50-60, and are found in men more often than women. Tumors are of mixed density (hypodense to isodense). High-attenuation areas within the tumour are likely from calcification (70-90% of oligodendrogliomas are calcified) or, less commonly, hemorrhage. Calcification can be located centrally, peripherally or they can be ribbon-like. The overlying skull may show pressure erosion.
The first and sometimes the only symptom of oligodendroglioma are seizures. Approximately 80% of patients experience seizures in varying degrees from mild to severe. Other symptoms can include headaches, vision loss, and motor weaknesses. The exact functions affected depend on the location and size of the tumor and how it is affecting the areas surrounding it. Gliomas can be slow-growing or fast-growing. Gliomas can be graded from 1 to 4. Low-grade tumors (grades 1 and 2) are slow-growing. High-grade tumors (grades 3 and 4) grow faster.
If the tumor is accessible, standard treatment for oligodendroglioma is surgical removal of as much of the tumor tissue as possible. Biopsy is typically performed on tumors that are not accessible to confirm the diagnosis and determine the grade of tumor. Recurrent low-grade oligodendrogliomas can be treated with surgery, radiation therapy (if not given initially), and chemotherapy.
Oligodendroglioma (Brain Cancer)
Oligodendrogliomas are a rare type of tumour that usually starts in the brain or sometimes the spinal cord. Oligodendrogliomas most resemble oligodendrocytes, the cells that encircle and insulate the nerve cells of the brain. They belong to the group of brain tumors known as gliomas as they develop from a type of glial cell known as an oligodendrocyte. These tumors can be found anywhere within the cerebral hemisphere of the brain, although the frontal and temporal lobes are the most common locations. Oligodendrogliomas are generally soft, grayish-pink tumors. They often contain mineral deposits (called calcifications), areas of hemorrhage, and/or cysts. Under the microscope, these tumor cells appear to have “short arms,” or a fried-egg shape.
A person with an oligodendroglioma may display one or more of these symptoms:
- Headaches (not alleviated by pain killers and are worse in mornings associated with nausea and vomiting)
- Mental status change (general changes in brain function)
- Vertigo or nausea
- Visual loss (altered vision or visual hallucinations)
- Muscular weakness and loss of control of bodily movements (weakness down one side of body)
- Altered sensations (strange smells, hallucinations relating to sense of smell)
Oligodendrogliomas are divided into two grades:
- Grade 2 (low grade) oligodendrogliomas; these are very slow growing
- Grade 3 (high grade) anaplastic oligodendrogliomas; these are a faster growing and malignant type
The majority of oligodendrogliomas occur in the frontal lobe, and the second most common site affected is the temporal lobe.
- Grade 3 oligodendrogliomas are more common in older people aged 60-80, but can affect any age. Oligodendrogliomas are slightly more common in men than in women.
Oligodendroglioma treatment depends on the grade and location of tumor.
- If surgery can be done, it is used as the first treatment to remove as much of the tumour as possible.
- Surgery is followed by radiation therapy, with or without chemotherapy.
- External beam radiation therapy is used following surgery, with or without chemotherapy.
- It may also be given as the main treatment, if surgery is not an option.
Chemotherapy may be used:
- The most common chemotherapy drug used is temozolomide (Temodal).
- Combination chemotherapy is usually given to treat anaplastic oligodendroglioma. The most common chemotherapy combination used is procarbazine hydrochloride, lomustine and vincristine.