June 20, 2025
Mayo Clinic has developed an approach to treating arteriovenous malformations (AVMs) that improves on standard stereotactic radiosurgery (SRS). An enhanced form of proton beam therapy is used to precisely target AVMs while avoiding the exit doses experienced with SRS.
"We're bringing together the best of radiosurgery and proton beam therapy. It's a revolutionary way to treat AVMs, and the preliminary data look very promising," says Bernard R. Bendok, M.D., chair of Neurosurgery at Mayo Clinic in Phoenix/Scottsdale, Arizona.
Although rare, brain and spinal AVMs can have devastating consequences, including hemorrhage, seizures, neurological deficits and spinal cord infarction. Treatment generally involves neurosurgery. But radiosurgery might be needed for large AVMs or those located near critical structures, such as the optic nerves, brainstem or spinal cord.
Mayo Clinic's experienced neurosurgeons work closely with radiation oncologists to provide that care. Neurosurgeons and radiation oncologists also collaborated on the research and development that produced the new AVM treatment.
"Our initial form of proton beam therapy had some physical limitations in terms of the beam's sharpness. We've worked to sharpen the lens of the beam, which allows for more precision," says Sujay A. Vora, M.D., a radiation oncologist at Mayo Clinic's campus in Arizona. "It allows us to give high-dose radiation more safely, reducing collateral radiation to healthy tissues."
Optimal management of AVMs is challenging, as they vary greatly in terms of risks posed to patients. The various treatment approaches also involve risks and benefits that must be weighed.
"This new approach combining the best of SRS and proton therapy offers another alternative for patients," Dr. Bendok says. "We need to learn more. But ultimately, this could be better than standard SRS."
Precise treatment for spinal tumors
Proton stereotactic body radiotherapy (SBRT) is used routinely to treat spinal tumors. "It's a highly precise form of radiation therapy, due to its ability to conform the radiation dose tightly to the tumor's shape," says Joshua Bakhsheshian, M.D., a neurosurgeon at Mayo Clinic's campus in Arizona. "That precise dose distribution is needed to avoid radiation-induced damage to the spinal cord."
Dr. Baksheshian notes that SBRT is particularly beneficial for treating spinal metastases and primary chordomas. "Stereotactic body radiotherapy offers high rates of local control and pain relief with low toxicity. The dosimetric advantages of proton stereotactic radiotherapy enhance those outcomes," he says. "The risk of radiation-induced myelopathy and other complications is reduced."
SRS and SBRT require precise imaging. Mayo Clinic's subspecialized neuroradiologists have extensive experience with these technologies. "One of the main challenges is to maximize the sensitivity and specificity of our imaging techniques to detect tumor and to distinguish these regions from normal tissues," says Leland S. Hu, M.D., a neuroradiologist at Mayo Clinic's campus in Arizona.
Contrast-enhanced MRI is a conventional approach to defining tumor burden. But recent studies have indicated that substantial tumor burden can extend beyond the areas of MRI enhancement. Mayo Clinic's clinician-researchers are pioneering the use of F-DOPA positron emission tomography (PET) scanning to detect these tumors regions.
"We hope to expand the applications of these complementary imaging techniques to elevate the standard of care, including the use of SRS, for a growing number of our oncology patients," Dr. Hu says. "The precision of imaging can affect the efficacy of cancer therapy, the avoidance of unintended side effects and overall clinical outcomes for our patients."
Mayo Clinic has a long history of embracing technology. Dr. William Worrall Mayo and his wife, Louise, mortgaged their house in 1869 to buy a microscope to help treat patients.
"We've always been at the forefront of innovation, looking for ways to provide patients the next best treatment," Dr. Vora says. "We're fortunate to have the know-how and time to get our good ideas across the finish line and offer something novel to patients."
For more information
Proton Beam Therapy Program. Mayo Clinic.
Refer a patient to Mayo Clinic.