Ground-Breaking Researcher and Leading Brain Tumor Surgeon Cites Strong Clinical Value of Cesium-131 Brachytherapy

In the past decade we’ve seen several prominent figures afflicted with Glioblastomas, highly malignant brain tumors comprised of astrocytes (star-shaped cells), that compromise the supportive tissue of the brain. While these high-profile cases have raised awareness of this deadly disease, modern medical science still struggles to treat it, and long-term prognoses are often grim in many cases.

But surgeons such as Dr. Theodore Schwartz, Professor of Neurosurgery, Otolaryngology and Neuroscience, as well as Co-Director of Surgical Neuro-Oncology at Weill Cornell Medicine, seek to change the outcomes for Glioblastoma patients. Dr. Schwartz’s interest in brain physiology started with his undergraduate work in philosophy and English, where he became interested in how language is organized in the brain. This ultimately evolved into an 18-year focus on minimally invasive endoscopic approaches to remove brain tumors.

During this time, Dr. Schwartz has learned that a good brain tumor surgeon is always looking ahead, preparing for the next phase of treatment. When facing conditions that spread cancer such as brain metastases and atypical meningiomas, a surgeon needs to become an expert on different modalities that are available to treat patients after surgery. Dr. Schwartz began to collaborate with a radiation oncologist, looking at treatments such as whole brain radiation therapy, stereotactic radiosurgery and brachytherapy.

The challenges of post-surgical treatment

“The issue with whole brain radiation therapy after surgery is that it treats the entire brain, including normal brain tissue,” explained Dr. Schwartz. “That’s unacceptable in most patients because you do not want to damage their normal brain.”

“Stereotactic radiosurgery is a terrific treatment that can be very effective, but it does require the patient to come back for an additional procedure several weeks after surgery,” the surgeon continued. The patient is still recovering from their brain tumor surgery, they’re about to probably embark on chemotherapy, and it’s not easy for them to come back into the hospital at that stage. Stereotactic radiosurgery also does not work so well for large cavities. If you remove a tumor that’s bigger than two or three centimeters, the efficacy rates go down. And they go down pretty dramatically.”

Brachytherapy shows new promise

Brachytherapy looked encouraging, but previous seed design and the isotope were not optimal. But when Cesium-131 became available, Dr. Schwartz consulted with the radiation oncologist and decided to apply it to the highest volume patient population where it would make the biggest difference: brain metastases that were large enough to require surgery. In these cases, the radioactive seed could be implanted during the surgery, easing the burden on the patient.

“Using Cesium-131 brachytherapy was advantageous for several reasons,” shared Dr. Schwartz. ”The first is that that dose is essentially distributed in about 3 weeks. Patients don’t need to be isolated or worry about radiating people around them for a long period of time. Second, since the dose falls out very quickly, there’s very little exposure given to the surrounding normal brain tissue. Third is that the seeds start working immediately. And since the seeds are laid around the cavity that you’ve removed, they work directly on the area of interest right from the start.”

Dr. Schwartz recently participated in a study on another advantage of Cesium-131 brachytherapy. “The seeds come on a string and they come sterile,” the physician explained. “When you line them in a cavity in the brain, the strength of the string, combined with fiber and glue that we add, allows the cavity to stay open.” Study data showed that Cesium-131 patients exhibited significantly less cavity shrinkage than stereotactic radiosurgery patients during the first critical month after treatment. This suggests that the intracavitary seeds-on-a-string technique facilitates the maintenance of the cavity volume, promoting better dose delivery.

“It just made sense on so many levels to try this,” said Dr. Schwartz. “When we started doing it, it was very well tolerated by patients and the results were truly astounding. We’ve had no recurrences of tumor within the cavity where we’ve put the seeds, which is really amazing. While we’ve had some very rare recurrences adjacent to where the seeds were, those tumors probably would have recurred anyway, even with other treatments. And the radiation necrosis rate is extremely low, much lower than stereotactic radiosurgery. On all accounts, it seemed brachytherapy was outperforming stereotactic radiosurgery for treatment of single brain metastases, particularly the larger ones.”

Long-term outlook of Cesium-131 brachytherapy

Dr. Schwartz has now worked with Cesium-131 brachytherapy for the past 7-8 years. “The rates of tumor control over time have been really remarkable, and we’ve seen very, very few—if any—recurrences,” he said. “As time has gone on and we have longer follow ups, it actually has increased our enthusiasm for Cesium-131, particularly for resected brain metastases. We’ve only seen one patient that looks like they developed radiation necrosis, and they’re now about 7-8 years out from treatment. That’s significant considering that most people who have brain metastases tend to live about a year. If you’re preventing recurrence in a patient, then you’ve done very well by them. I believe that conversations on brachytherapy need to be held openly with patients so they understand that there are options that can help.”

Looking to the future, Dr. Schwartz believes that brachytherapy is going to be increasingly used in applications based on synergy with medications. He feels it may be possible to combine radiation therapies with medications that make the tumor more sensitive to the radiation, and also make the brain less sensitive to the radiation. The surgeon also supports continued research into combining radiation treatment with better chemotherapy and immunotherapy.

“If there is a silver lining, to these unfortunate public figures who have given so much to our country, and who were struck down by a disease that we can’t yet manage appropriately, it’s the hope that more funding and donations will go toward research into these types of brain tumors,” the surgeon concluded. “We also need more young brilliant minds to go into this field.”

Theodore H. Schwartz, M.D.


  • Attending Neurological Surgeon at New York-Presbyterian Hospital
  • Professor of Neurological Surgery in Otolaryngology at Weill Cornell Medical College, Cornell University
  • Professor of Neurological Surgery at Weill Cornell Medical College, Cornell University
  • David and Ursel Barnes Professor of Minimally Invasive Neurosurgery at Weill Cornell Medical College, Cornell University
  • Professor of Neuroscience at Weill Cornell Medical College, Cornell University
  • Named one of New York’s Super Doctors, Best Doctors in New York Magazine, America’s Top Surgeons, America’s Best Doctors and America’s Best Doctors for Cancer
  • Co-author of two books on endoscopic skull base surgery and endoscopic pituitary surgery
  • Graduated Magna Cum Laude from Harvard Medical School in 1993

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