Imagine focusing hundreds, or even thousands, of radiation beams on a cancerous tumor, hitting it hard with high-precision doses of radiation.
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It’s called Stereotactic Body Radiation Therapy (SBRT). While the technique is not new, it’s now become available to treat colon cancers that have spread to a person’s liver.
Doctors have used SBRT in the U.S. over the last 15 years to treat lung, liver, prostate or spinal tumors. Expanding its use is an exciting development, in part, because it’s a super-charged treatment. It can do in one to five sessions what standard radiation takes 20, 30 or even 40 sessions to accomplish.
It also can help patients who have cancer that has spread from the initial site to other areas of the body. This can give hope to patients with more advanced cases.
For cancers that have spread
While a powerful weapon against cancer, SBRT is not right for every tumor. Colon cancers that have stayed “local” are typically best treated with surgery, says radiation oncologist Kevin Stephans, MD.
But for about the past decade, SBRT has provided an effective method for those that have spread to the liver. It is non-invasive, and compared to standard radiation, it is significantly cheaper, more convenient and has fewer side effects.
“SBRT has had great results to date,” Dr. Stephans says.
How it works
During SBRT treatments, radiation oncologists use image-guiding machines to make sure they’re “hitting the right spot,” Dr. Stephans says.
First, to help patients hold their breaths, they place an active breathing control (ABC) machine over the patient’s mouth help them hold their breath consistently. This is necessary because the liver moves up and down as you breathe, and it’s important that patients stay still.
Oncologists work on the tumor(s), continually pausing the treatments so patients can take a few good breaths before continuing. The treatment takes about 20-30 minutes (with only about three to six minutes of total breath-hold time for patients, which comes in 15- to 20-second spurts).
An effective alternative
Surgery is also used to treat colon cancer that has metastasized to the liver. This method is the “most tried and true” but also the most invasive.
Radiofrequency ablation is another treatment option. During the procedure, a needle inserted into the tumor works to “freeze or fry it,” Dr. Stephans says.
“SBRT offers a non-invasive alternative,” he says. “It allows delivery of a high-dose of radiation where the beams cross and destroy the DNA of the tumor, so the cells can’t divide.”
Who is the best candidate for SBRT? Dr. Stephans says the most appropriate patient is someone with a relatively limited number of liver metastases. A patient who has a large number would be better suited for systemic therapy. To offer the best patient care, a multidisciplinary tumor board meets to discuss each patient’s case.
As the biggest advantage of SBRT is the ability to provide non-invasive therapy, those who would benefit most are patients who are at risk of surgical complications or those who favor an alternative therapy that does not require hospitalization.