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Radiation Therapy for Brain Cancer

  • Certain therapy treatments can efficiently target cancerous tumors in the brain
  • Symptoms of brain cancer include loss of vision, nausea, persistent headaches, and seizures
  • Treatment involves radiation therapy or a radiation beam
  • Involves Central Nervous System Radiotherapy, Head & Neck Radiotherapy, and brain tumor program

Overview

It can be scary to receive a brain cancer diagnosis. As a patient, you might have a lot of questions: Is it treatable? Will it affect my daily life? What are my chances of survival? Every year, nearly 24,000 people are diagnosed with cancer of the brain or nervous system. Brain cancer (also known as a primary brain tumor) affects children and adults, and often attacks at random. There aren’t any well established lifestyle factors known to increase risk.

Treating the brain can be tricky, because it is such a delicate structure. Fortunately, new targeted radiation therapies at Yale Medicine allow doctors to remove tumors without affecting the rest of the brain. 

What are the types of brain tumors?

There are two types of brain tumors: gliomas, which form in the supporting tissue (the “glia”) of the brain, or meningiomas, which form in the tissue covering the brain and spinal cord (the “meninges”). The most common type of glioma, a glioblastoma, is one of the most aggressive types of brain cancer.

Once diagnosed, gliomas are divided into four grades:

  • Grade I: Benign
  • Grade II: Moderately aggressive and slow growing
  • Grade III: Aggressive
  • Grade IV: Very aggressive

Meningiomas, on the other hand, are usually benign, meaning they don’t spread to other parts of the brain.

Other types of brain tumors include pituitary tumors and pediatric brain tumors, such as ependymomas and medulloblastomas.

Cancers that originate in other parts of the body can also spread to the brain, and those are referred to as secondary (or metastatic) brain tumors.

What are the symptoms of brain cancer?

Brain tumors often grow quite large before they cause any symptoms. “They may be in parts of the brain that don’t affect normal functioning, or the brain can rewire itself to adjust and work around the tumor,” says Ranjit Bindra, MD, PhD, a radiation oncologist in the Department of Therapeutic Radiology.

Eventually, though, a tumor can grow large enough so that pressure builds up inside the skull, or presses against spinal fluid or nerve tissue. “Suddenly, the plumbing inside the brain gets stopped up,” says Dr. Bindra.

This may cause any of the following symptoms:

  • Loss of vision
  • Nausea and vomiting
  • Persistent headaches
  • Seizures
  • Trouble speaking

How is brain cancer diagnosed?

Depending on the patient’s symptoms, a physician will perform different tests and a full physical exam to rule out other conditions.

Then the patient will undergo imaging tests of the brain, such as a computed tomography (CT) or magnetic resonance imaging (MRI) scan.

“MRI is usually the most important test because it really shows the minute details of the brain’s soft tissue,” says Dr. Bindra.

If a suspicious tumor is detected, surgery is performed to remove either the whole thing or a small piece in a biopsy procedure, so that tissue can be analyzed under the microscope by a pathologist to see whether cancerous cells are present.

Doctors will also assign the tumor a grade based on how likely it is to keep growing, which will determine the course of treatment going forward.

What are risk factors for brain cancer?

Compared with other cancers, we know relatively little about the risk factors for brain cancers. 

“It’s not like lung cancer or breast cancer, where you clearly have an elevated risk from smoking or other well-defined factors,” says Dr. Bindra. “A lot of it is luck of the draw.”

Still, the following are factors associated with increased risk for brain tumors:

  • Age (brain cancers occur more frequently in children and older adults)
  • Radiation exposure as a child
  • Rare genetic mutations
  • Weakened immune system

Scientists have investigated potential links between brain tumors and environmental exposures, such as cell-phone radiation, petroleum products and artificial sweeteners, but evidence supporting such links has been weak or inconclusive.

How is brain cancer treated?

Benign or slow-growing brain tumors (Grades I or II) are often treated with surgery alone, while more aggressive tumors are treated with radiation therapy, surgery or a combination of two more of these options. Chemotherapy drugs are often used too, but because the body’s blood-brain barrier is so effective at keeping foreign chemicals out of the brain, some drugs cannot cross the barrier to reach the brain tumor.

In many cases, surgery is the best option to remove part or all of a tumor can save a patient’s life. In other cases, such as when tumors are very small or in locations too difficult to operate on, doctors will give chemotherapy or radiation therapy alone.

At Yale Medicine, we use a newer type of targeted radiation therapy (known as radiosurgery). This type of radiation therapy has fewer side effects than previous radiation therapies that treated the entire brain. The newer type of targeted radiation (also known as radiosurgery) is planned using brain scans and delivered via one of two instruments:

Conformal radiation therapy. A patient lies on a table and wears a mask molded to the face, while the linear accelerator rotates around him or her and beams radiation at the tumor(s). This procedure can be used to treat larger tumors in several sessions over about six weeks. Treatments can last up to an hour, but many span fewer than 15 minutes.

Gamma Knife. A patient wears a metal “frame” around the head, with anchored screws. This frame lets the Gamma Knife machine know exactly where to aim the radiation beam so it can destroy the cancer cells but not the surrounding healthy tissue. This procedure is best for targeting small tumors and usually completed in a single session lasting a few hours.

These types of radiation may cause side effects including fatigue and skin irritation. Depending on how much radiation is needed, and what part of the brain is targeted, other side effects, such as headache, nausea, hair loss and/or memory problems may also occur. These side effects are much less common with targeted Gamma Knife or focused radiation therapy than they are with older, whole-brain radiation techniques.

How is Yale’s approach to treating brain cancer unique?

Patients benefit from Yale Medicine’s multidisciplinary approach to treating brain cancer. Each case is presented to a tumor board, where doctors from several departments, including neuro-oncology, neurosurgery, radiation oncology and neuroradiology, discuss and collaborate to decide on the best course of action for each patient.