Stereotactic Radiosurgery

What is stereotactic radiosurgery?

Stereotactic radiosurgery (SRS) is a form of radiation therapy that primarily treats small brain tumors. Although “surgery” is in the treatment name, SRS doesn’t involve traditional surgical incisions (cuts). Instead, a machine directs tiny beams of high-dose radiation to the diseased tissue. The beams come from different directions and intersect at the exact spot where the tumor is. They deliver radiation to the target area while sparing healthy tissue.

You may be a candidate for stereotactic radiosurgery if you have a brain tumor that needs to be removed, but traditional surgery is too risky. For example, the tumor may be too close to vital blood vessels or other structures. Or you may need it after surgery to kill any remaining cancer cells.

Radiation oncologists and neurosurgeons use SRS to treat benign (noncancerous) and cancerous tumors, including:

• Acoustic neuroma
• Chordoma
• Craniopharyngioma
• Glioblastoma
• Glioma
• Hemangioblastoma
• Meningioma
• Metastatic brain tumors
• Paraganglioma
• Pineoblastoma
• Pituitary adenoma

Your provider may also use SRS to prevent abnormal brain tissue from causing symptoms. SRS can seal abnormal blood vessels in your brain (arteriovenous malformation) that can cause bleeding. It can block nerve signals from reaching your brain and causing pain. This is what happens when SRS treats trigeminal neuralgia.

Sometimes, stereotactic radiosurgery treats tumors outside of your brain. SRS treats tumors in your liver, lungs and pancreas. Radiosurgery that treats tumors in your body (not in your brain) is called stereotactic body radiation therapy (SBRT).

How should I prepare for this procedure?

To help you prepare, your care team will:

• Review your medical history
• Explain the procedure, so you know exactly what to expect
• Let you know when to fast (stop eating or drinking fluids except water)
• Tell you if you should stop taking medicines before treatment
• Tell you how to get ready the day of your procedure (for example, you shouldn’t wear jewelry or makeup)

What happens during stereotactic radiosurgery?

During SRS, your healthcare provider controls a computer that operates the SRS unit. You’ll be in the room with the SRS unit, while your provider operates the computer in a separate room. The computer has imaging technology that shows the treatment area. This helps your care team get you in position. Sometimes, it shows the tumor during treatment. This is called image-guided radiation therapy.

Your exact experience depends on the type of SRS unit. There are three main types:

• Gamma Knife^®. In this procedure, you’ll lie on a treatment table, with your head secured in a frame or mask. The table will slide into a treatment unit so just your head is inside. Then, the unit will send the radiation beams toward the tumor.
• Linear accelerator (LINAC). In this type, you’ll lie on a treatment table, with your head secured. An arm attached to the unit will move in arcs around you. As it moves, it sends X-rays toward the tumor. Sometimes, this type is called Cyberknife^® or Varian Edge^®.
• Proton therapy. This treatment delivers concentrated streams of high-energy particles toward the treatment area. This type of SRS is newer and less common.

During treatment, you can expect your medical team to:

1. Review what you can expect. This includes demonstrating the intercom system. You’ll be able to speak with your care team the whole time.
2. Help you onto the treatment table and put immobilization devices in place. You may need to wear a head frame or mask to keep you from moving during treatment. Staying still prevents healthy tissue from being exposed to radiation.
3. Do imaging scans. Tests include MRIs, CT scans and (in some cases) angiograms. Your team will pinpoint the tumor location so they can design radiation beams that target it.
4. Design treatment. Your team will decide if you’ll get a single high dose of radiation or smaller doses over several sessions. Smaller doses spread out are called “fractionated treatment” or “stereotactic radiotherapy.”
5. Deliver the treatment. You’ll receive the radiation treatment from the SRS unit. Stereotactic radiosurgery isn’t painful, so you won’t feel anything. But you might hear the machinery moving into place.

How long does this procedure take?

The procedure may take one to four hours. Much depends on the type of SRS you get and how long it takes to design your treatment. If you’re getting Gamma Knife treatment, your team will design the treatment and deliver it the same day. If you’re getting LINAC radiosurgery, you’ll likely have one appointment where your team designs the treatment. Then, you’ll need one or more separate appointments to receive it.

Most people get treatment in a single session. But with fractionated treatment, you get smaller doses spread out over three to five sessions.

What are the potential benefits and risks of stereotactic radiosurgery?

Stereotactic radiosurgery can destroy or shrink tumors. As there aren’t any incisions, it has fewer risks than surgery. It causes milder side effects than radiation directed to your entire brain (whole-brain radiation therapy). Also, most people are in and out of treatment in a single visit.

Still, there are potential risks that your healthcare provider will explain. They depend largely on the specific site that needs to be treated.

What happens after stereotactic radiosurgery?

Most people go home after treatment. But your care team may ask you to remain at the treatment facility for 30 minutes to a few hours so they can watch for any side effects. Common radiation therapy side effects include:

• Diarrhea
• Fatigue
• Hair loss
• Headaches
• Nausea and vomiting
• Skin changes

Your provider can recommend medicines to ease unpleasant symptoms.

How long does it take to recover from this procedure?

Side effects like fatigue, nausea and vomiting typically go away between one and two days to a few weeks. Hair usually grows back within two to three months after treatment.

You’ll likely need a follow-up visit around the one-month mark to see how you’re doing. You may need a neurological exam to check for late effects from treatment. Within a few months, you’ll get imaging scans to see how the tissue is responding to treatment. For instance:

• Cancerous tumors tend to shrink within a few months.
• Benign tumors typically show signs of improvement within a year or two.
• Symptom relief from trigeminal neuralgia may take weeks to months.

When should I call my healthcare provider?

Tell your healthcare provider if you have symptoms that may be late effects of stereotactic radiation therapy. They’ll work with you to manage side effects. They may prescribe medications like corticosteroids to reduce brain swelling. Your provider may also recommend:

• Speech therapy
• Occupational therapy
• Physical therapy

What is the success rate of stereotactic radiosurgery?

Success rates vary depending on your health and the condition being treated. According to a recent study, SRS to treat small brain cancers is as effective as whole-brain radiation. And it’s less likely to cause late side effects. But this is just one potential scenario.

Ask your radiation care provider what you can expect based on your situation.