Glioma

A tumor is a mass or growth of abnormal cells. Tumors found in the brain typically are categorized as primary or secondary. Primary brain tumors (gliomas) start in the brain or spinal cord tissue. They can spread within the nervous system but typically do not spread outside the nervous system.

Gliomas can be either low-grade (slow-growing) or high-grade (fast-growing). Annually, about 17,000 Americans are diagnosed with gliomas.

Treatment for brain tumors can be challenging, but many are treated successfully. New technology helps physicians target tumors more precisely and innovative treatments under investigation offer opportunity for the future.


DIAGNOSIS

Diagnosing a brain tumor usually begins with an exam by a neurologist, which includes checking vision, hearing, balance, coordination and reflexes. Depending on those results, the physician may request one or more of the tests described below. A biopsy is usually required to diagnose a brain tumor and confirm its type.

Magnetic Resonance Imaging (MRI) Scan
This scan uses magnetic fields to generate images of the brain. The patient lies inside a cylindrical machine for approximately an hour. MRI scans are particularly useful in diagnosing brain tumors, because they outline the normal brain structures in detail. Sometimes a special dye is injected into the bloodstream during the procedure to help better distinguish tumors from healthy tissue (MRI angiogram).

Computed Tomography (CT) Scan
A CT scan uses a sophisticated X-ray machine linked to a computer to produce detailed, two-dimensional images of the brain. A patient lies still on a movable table that is guided into what looks like an enormous doughnut where the images are taken. A special dye may be injected into the bloodstream after a few CT scans to help better distinguish tumors (CT angiogram). A CT scan is painless and generally takes less than 10 minutes.

Angiogram
A special dye is injected into the arteries that go to the brain. The dye, which flows through the blood vessels in the brain, can be seen on X-ray. This test helps locate blood vessels in and around a brain tumor.

Other Brain Scans
Magnetic resonance spectroscopy (MRS), single-photon emission computed tomography (SPECT) or positron emission tomography (PET) scanning also help physicians gauge brain activity and blood flow. These scans can be combined with MRIs to help physicians understand a tumor's effects on brain activity and function. If a brain scan detects a tumor, especially multiple tumors, physicians may test for cancer elsewhere in the body.

X-rays of the Head and Skull
An X-ray of the head may show skull alterations indicating a tumor or calcium deposits sometimes associated with brain tumors. However, an X-ray is far less sensitive than brain scans and is used less often.

Biopsy
A biopsy is usually required to diagnose a brain tumor and confirm its type. In a biopsy, a tiny piece of tumor is removed for examination under a microscope. A biopsy can be performed separately or as part the surgery to remove the tumor.


TREATMENT

New glioma treatments are developed continually, so several options may be available for patients. The pros and cons of each option are discussed in detail during treatment planning.

Treatment options and survival odds depend on the glioma type, size and location, as well as the patient's age and overall health. For treatment specifics, see descriptions of each glioma type:

• Astrocytomas
• Ependymomas
• Glioblastoma multiforme
• Oligodendrogliomas
• Mixed gliomas

Quality of Life
As glioma treatment becomes more successful, patients live longer but also face greater risks of long-term adverse effects of treatment. The most significant adverse effects are cognitive problems. Mayo specialists, including neuropsychologists and experts in brain rehabilitation, help patients with these issues. Almost all clinical trials at Mayo Clinic and the North Central Cancer Treatment Group incorporate quality-of-life measures.

Whenever possible, the glioma treatment team integrates care from the patient's local physician and oncologists to offer the most comprehensive treatment program management.


Treatment Options


Surgery
Surgery is the initial therapy for nearly all patients with gliomas. It can cure most benign gliomas, as well as meningiomas. The goal of surgery is to remove as much of the glioma as possible while minimizing damage to healthy tissue.

Some gliomas can be removed completely; others can be removed only partially or not at all. Partial removal helps relieve symptoms by reducing pressure on the brain and reducing the size of the glioma to be treated by radiation or chemotherapy.

Direct, face-to-face contact with the pathologist during the surgery allows the surgeon to verify that the glioma has been fully removed and may reduce the need for an additional operation.

If a glioma cannot be surgically removed, the physician may do only a biopsy. A small piece of the glioma is removed so a pathologist can examine it under a microscope to determine its cell makeup. The finding helps determine the proper treatment.

Patients diagnosed with brain gliomas often can be scheduled for surgery the next day, if desired. Surgeons provide patients with information to help them decide which treatment is best for them. Surgical removal demands great skill. Mayo's neurosurgeons operate on hundreds of patients each year, using the latest technological advances. Mayo surgeons were pioneers in developing computer-assisted neurosurgery, which allows surgeons to precisely map the brain and more accurately and aggressively treat brain tumors.


Radiation Therapy
Radiation Therapy is an essential component of treatment for many patients with gliomas. It can be curative some patients and prolongs survival for most.

The traditional form of radiation therapy, referred to as fractionated radiation, delivers radiation in small doses (fractions). Typically, patients are treated once daily, five times per week, for a total of five to six weeks. Even after the tumor visible on the CT or MRI scan is removed, radiation is often used to treat the margin of brain around the surgical cavity, going after the microscopic tumor cells that have infiltrated the area from the original mass.

External Beam Radiation
This traditional form of radiation therapy delivers radiation from outside the body. The radiation usually involves treatments five days a week. The length of treatment time depends on the type of glioma. External beam radiation is less precise than Fractionalized Stereotactic Radiotherapy, but allows a wider area of tissue around the glioma to be treated.

Fractionalized Stereotactic Radiotherapy (FSR)
Fractionalized Stereotactic Radiotherapy minimizes damage to healthy tissue by carefully targeting radiation. FSR involves many small treatments instead of one big dose of radiation. Healthy brain tissues and cranial nerves that cannot tolerate a single, large treatment can tolerate many small treatments.

This treatment also offers the biological benefit of fractionation (separation into different portions) to exploit the different sensitivities of healthy versus cancerous tissue. These advantages are helpful when treating lesions near delicate structures such as the optic nerves, which cannot tolerate high levels of radiation.

For FSR, the glioma patient is fitted with a plastic mask that helps locate the glioma and target the radiation during treatment. The patient lies on a table. X-rays are taken to determine correct positioning. The treatment is given in several small units called arcs. The number of treatments depends on the size and location of the glioma.



Stereotactic Radiosurgery
Stereotactic Radiosurgery is effective for lesions such as meningioma or small brain metastases that are confined to a limited area. It spares nearby healthy tissue because radiation levels drop rapidly at the edges of the area being treated.

Radiosurgery is not typically used in the treatment of gliomas. Gliomas tend to be infiltrative tumors, so the areas around the surgical cavity or around the visible tumor mass are not ideal targets for radiosurgery. Fractionated radiation is used most often.

Chemotherapy
Chemotherapy is an important part of the care of glioma patients. For patients with glioblastoma (Grade 4 astroccytoma), the most rapidly growing and aggressive glioma, the addition of chemotherapy to the radiation has been shown to significantly extend a patient's lifespan. Current research is focused on the development and evaluation of new drugs to use with radiation for a newly diagnosed tumor, as well as for recurrent gliomas.