A cure has not yet been identified for diffuse glioma. Surgical resection, radiation therapy, and chemotherapy are the primary treatment options. The location, size, and subtype of glioma determine which combination of treatments is best.
Diffuse glioma tumors grow into (infiltrate) the surrounding brain tissue. A distinct boundary between the tumor and the healthy brain does not exist. During surgical resection, the benefit of removing tumor cells must be balanced with the risk of removing healthy brain tissue.
Surgical resection aims to remove as much tumor as possible while minimizing the risk to normal brain tissue. Surgical resection reduces the amount of tumor tissue within the brain (tumor debulking), improves response to radiation and chemotherapy, relieves symptoms, and lowers intracranial pressure.
Preoperative imaging and various intraoperative techniques are used to maximize tumor resection and minimize damage to the normal brain. Some intraoperative methods include:
- Neuronavigation (intraoperative MRI)
- Motor mapping (movement stimulation)
- Fluorescent dyes that color the tumor
- Awake surgery with ongoing assessment of movement and language ability
Unfortunately, some tumor cells inevitably remain. These continue to grow and eventually lead to a recurrence of the tumor. Although not curative, surgical resection may prolong survival and improve the quality of remaining life.
Surgical intervention may not be recommended for some people with glioma. In selecting surgical candidates, neurosurgeons consider the rate of growth of the tumor and the presence of other symptoms (increased intracranial pressure, bleeding into the tumor, persistent seizures). They also consider the tumor's location: if it is in a critical area of the brain, the risk of damage may outweigh the benefit of tumor resection.
Radiation therapy (RT) uses ionizing radiation (high-energy beams) to kill tumor cells. RT is frequently prescribed to kill residual (remaining) tumor cells two to four weeks following surgery. It can also be used when surgical resection is unsafe or to relieve symptoms later in the disease course.
RT kills tumor cells by damaging DNA. Normal brain cells are also damaged but are faster to recover. The amount of radiation delivered to normal cells is minimized by carefully selecting the radiation field (area to receive the radiation), the total radiation dose, the timing of treatment, and the delivery method.
In external beam radiation therapy (EBRT), radiation directed at the tumor is delivered from outside the body using a special machine. Radiation oncologists use CT and MRI scans and sophisticated software to develop a treatment plan and target the glioma. Treatment is usually delivered in a series of treatments called fractions over several weeks.
Stereotactic radiosurgery is another form of radiation therapy suitable for small tumors. This technique is not surgical (despite its name) but delivers radiation to the tumor from outside the body. It uses many small beams of radiation directed at a point within the tumor. Treatment usually takes place in a single session.
Proton therapy is a radiation technique that uses protons instead of traditional x-rays. Proton therapy may be used in critical brain areas where damage to nearby tissues would not be tolerated.
Short-term side effects of RT usually occur within six weeks of treatment and include fatigue, hair loss, rash, and decreased appetite. Headaches, nausea, and a worsening of neurologic symptoms (seizures, weakness) may also occur.
Cognitive impairment (mild memory loss, confusion, decreased ability to perform complex tasks, poor concentration) sometimes develops months later. It may be caused by the RT, the chemotherapy, or the glioma itself.
Other long-term side effects are cataracts, and rarely, hearing loss, hormonal changes, new tumors, and radiation necrosis (dead tissue formed at the site of radiation).
RT is not curative but helps contain tumor growth and prolongs survival compared with surgery or chemotherapy alone.
Chemotherapy targets cells during their cell cycle when cells are in the process of multiplying. Because cancer cells form new cells faster than most normal cells, chemotherapy has a greater detrimental effect on cancer cells.
Glioma tumors are often treated with temozolomide or PCV (procarbazine, lomustine, vincristine). The drugs are taken orally (as a pill) or intravenously (through a vein).
Since chemotherapy targets rapidly dividing cells, it can affect normal cells that continue to be produced even in adult life, including hair follicles, cells that line the gastrointestinal tract, and blood cells. As such, typical side effects include:
- Increased risk of infection
- Bruising and bleeding
- Shortness of breath and fatigue
- Nausea and vomiting, constipation, and abdominal pain
- Numbness or tingling in fingers and toes, or weakness
- Hair loss
Treatment also includes managing symptoms caused by the glioma.
People who experience seizures are treated with an antiseizure drug, typically levetiracetam. Tumor-induced seizures can be challenging to treat, and surgical resection may be recommended to reduce seizure activity.
Glucocorticoids (steroids) can improve headaches and neurologic deficits caused by cerebral edema. Dexamethasone is frequently prescribed for this purpose but is associated with significant side effects and may shorten survival. Glucocorticoids are used at the lowest effective dose and, ideally, only until other treatments are planned.
Palliative medicine is a medical specialty focused on relieving the symptoms that people with serious illnesses endure. The goal of palliative therapy is to reduce the suffering caused by cancer and ensure the quality of life is maximized during cancer treatment.
Treatment for gliomas is an area of active research. Some treatment innovations are:
- Tumor treating electrical fields (Optune): A device worn on the scalp delivers alternating electrical fields to prevent the growth and division of cancer cells.
- Convention-enhanced delivery – Chemotherapy is slowly and continuously delivered to the tumor via a pump.
- Implanted chemotherapy wafer therapy (Gliadel) – Chemotherapy is released directly into the remaining tumor from a disc embedded during surgical resection.
- Nanoparticle therapy – Special particles allow chemotherapy drugs to cross the blood-brain barrier and improve access to the tumor.
Patients may also be eligible to participate in clinical trials to access new treatments under investigation. Learn more about our open clinical trials >