Stereotactic radiation therapy is a type of external beam radiation that delivers radiation to a tumor from many different angles. This kills the cancer cells or stops them from growing and spreading. It’s also called stereotactic ablative radiotherapy (SABR).

How is stereotactic radiation therapy different than standard radiation therapy?

Stereotactic radiation uses fewer treatment days than standard radiation. Each treatment day is called a “fraction.” With standard radiation, the total dose is split into many fractions over many weeks. With stereotactic radiation, there are fewer fractions, but each one gives a higher dose of radiation. The radiation comes from many angles to focus on a small area, which lessens the radiation given to normal tissue and lowers the risk of side effects.

Who can have stereotactic radiation therapy?

Stereotactic radiation is often used for small tumors (less than 5 cm) that are easy to see on scans like CT or MRI. It might not be used if your tumor is close to or touching your airways, heart, spinal cord, or other very important parts of your body. The size, shape, and where your tumor is, and the type of cancer you have, will be part of deciding if stereotactic radiation will be used for your treatment.

What are the types of stereotactic radiation therapy?

There are two types of stereotactic radiation therapy:

Stereotactic Radiosurgery (SRS)

SRS is not surgery, and there is no incision (cut in the skin).
It’s mostly used for small brain tumors.
Often, only one fraction of radiation is given.
You will have an MRI before SRS to help plan your treatment.
Your head will need to stay still during treatment, usually with an immobilization mask made just for you.
Your care team might include providers from neurosurgery and radiation oncology.

Stereotactic body radiation therapy (SBRT)

SBRT is often delivered in one to five high-dose fractions.
SBRT can be used to treat cancers like lung, prostate, liver, kidney, and pancreatic. It can also be used to treat spine tumors and metastatic cancer.
It is often used if you are not able to have surgery.
SBRT can use either photons or protons.
You will have a CT or MRI to help plan your treatment.
Small metal markers called “fiducial markers” may be placed in or near your tumor to help track the tumor during treatment. They are put into place using needles that are guided by ultrasound and will stay in your body.
You may also get small ink tattoos on your skin to help position you during treatment.
Special devices may be used to keep your body still, and you may need respiratory gating such as a compression belt or deep inspiration breath hold (DIBH), or an immobilization mask during treatment to keep the tumor in the same spot.

What can I expect after having stereotactic radiation therapy?

You may have side effects during or after SBRT or SRS, which depend on where your tumor is, the radiation dose, and the number of fractions. Because stereotactic radiation targets a small area, there tend to be fewer side effects than with standard radiation therapy. These side effects often go away, but some might happen weeks or months after treatment.