Stereotactic body radiotherapy (SBRT) is a precise, high-dose form of radiation therapy that allows physicians to treat cancer in just one to five treatments, rather than the multiple doses over many weeks required in conventional radiation. With SBRT's high level of accuracy and precision, doctors can target and eliminate tumors while avoiding normal tissue. That makes SBRT, which also has fewer side effects than conventional radiation, more effective.
At Yale Medicine, our doctors see a very high volume of patients and serve as a referral center for a wide variety of cases.
Who is eligible for SBRT radiosurgery?
SBRT is appropriate for patients who have small, clearly delineated tumors. For example, an early stage lung cancer patient whose only sign of disease is a 2-centimeter nodule, or someone with colon cancer whose metastasis in the liver is up to 5 centimeters in size, could benefit from SBRT. What matters most is that doctors can target the whole tumor because they can see and delineate it on imaging studies.
The nature of the neighboring tissue also factors into doctors’ decision, because they never want to damage a sensitive area. “The most common site is lung, early lung, or lung metastases,” says Roy Decker, MD, PhD, director of Yale Medicine’s Thoracic Radiotherapy Program. “The reason is they're surrounded by lung – by air.”
The liver is similarly accessible; Yale Medicine doctors also work on the prostate, the head and neck, and the base of the skull. They can even treat tumors near the spinal cord as long as they have a few millimeters of space.
How does SBRT work?
Although "surgery” is a part of the acronym, SBRT is a noninvasive treatment. During the procedure, doctors simply ask that a patient lie quietly and breathe normally.
The first part of treatment involves a consultation with one of our radiation oncologists, followed by a discussion of treatment options. Yale Medicine takes a multidisciplinary approach to treatment. In the case of lung cancer, radiation and thoracic oncologists will discuss the course of treatment. For spine cases, they work as a team with a neurosurgeon.
Once a plan is in place, you'll next have an hour-long simulation, during which Yale Medicine places you in an immobilization device and measures the motion your organs. “We have to account for motion of the tumor, that can be up to several centimeters,” Dr. Decker says. “After all, lungs move when you breathe.”
A week or two later, doctors begin the radiation, and, depending on the size of the tumor, its location and diagnosis, the process continues for up to five treatments, each lasting about half an hour.
How do you monitor the patient afterward?
SBRT is an ablative treatment, meaning that the goal is to destroy the tumor. While they hope that on completion of the treatment, the tumor is no longer a threat, doctors cannot tell right away whether the tumor is alive or dead. A computerized tomography (CT) scan only shows that there is a mass, and scar tissue may look like a tumor. Doctors evaluate the area during follow-up exams over several months to make sure that there are no unanticipated problems. Sometimes it may take a year or more of surveillance to be confident that a mass contains no living tumor.
After SBRT, Yale Medicine frequently follows patients indefinitely. For lung cancer patients, for example, even when doctors are confident that the treatment was successful, they will continue annual CT scans to screen the remaining lung tissue. That way, if a patient develops another tumor or a precancerous lesion, they can quickly plot a course of treatment.
What are some common side effects of SBRT?
About half of patients experience no side effects. A slight majority experience minor fatigue, but it’s not usually debilitating exhaustion. More serious side effects are very rare, and are often related to the specific size and location of the tumor that is targeted.
Are there any long-term risks to SBRT?
Any exposure to radiation carries a very small risk of causing a secondary tumor.
What makes Yale Medicine’s approach to SBRT unique?
As adept as Yale Medicine physicians and radiation therapists are at administering the treatment, they are equally adept at helping patients feel comfortable during the discussions and simulations. Yale Medicine has such a breadth and depth of experience, and so many doctors with subspecialties, that doctors can offer the patient the solace of undergoing treatment in a place where physicians have usually seen similar cases.
Yale Medicine’s multidisciplinary approach means that if the team wants additional consultations in individual instances, they can turn to skilled people across all departments.