Killing Tumors in Kids With Radiosurgery: New Advances

Kevin T. Murphy, MD


February 25, 2011

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Hello. My name is Kevin Murphy. I am Associate Professor at University of California San Diego (UCSD) in La Jolla, California, and I am Director of the Pediatric Radiation Oncology Program at UCSD and on staff at Rady Children's Hospital here in San Diego. I specialize in treating brain tumors in adults and pediatrics. We see approximately 100 patients per year with new cancers; approximately 50% of those patients have brain tumors and need radiation therapy. We are specializing in the use of radiosurgery in these cases, if possible.

The field of radiation oncology has changed immensely in the last 5-10 years with the advance of IMRT [intensified modified radiation therapy], IGRT [image-guided radiation therapy], image guidance, radiosurgery techniques with infrared technology, and then the "frameless" or "maskless" techniques for tracking patients during therapy as opposed to using bolted head frames. We have come a long way. Radiation therapy avoids anesthesia in some kids and allows us to treat kids as outpatients. Whereas even 5 years ago, it might take 30 minutes to give a brain tumor enough dose, nowadays we are doing outpatient therapies in 60 seconds. We are seeing a greater use of our technology being applied in primary brain tumors or metastatic tumors in both adults and children.

What we notice a bit differently in the population with primary tumors (and not metastases) is that the lesions are not visibly gone at the 3- to 4-month MRI checkup, as you would see with metastases. They are space-occupying lesions; they are parenchyma-occupying lesions; and they create a deficit following radiosurgery. There is a time interval of up to a year during which the lesions have to be watched to verify that they are going away. In the past, these kids were taken back to the operating room and had surgery to an area that had received radiosurgery, and only dead tissue was found. The defect might look bigger on the scans, but the actual tumor itself was dead.

We are trying to get to a point where we can avoid a lot of the unnecessary invasive surgeries; do outpatient radiosurgery; and treat not just the brain, but the spine and the lung and liver are becoming more popular. That is called stereotactic body radiosurgery, and we have patients with sarcomas that metastasize to the lung or liver who can avoid lobectomy, a liver surgery, or a laminectomy on the spine. This is a great use in kids who are ill and, in some cases, on hospice and are going to die but who need palliation of their tumor. It is also a great resource for treating patients who have had subtotal resections in the brain, and we can give a boost of energy (radiation therapy) as opposed to a larger surgery.

More and more, we are having surgeons do subtotal resections, leaving the "eloquent" parts of the brain unaffected and leaving small residual tumors open for radiosurgery techniques. In our frameless ability to do this, with outpatient procedures, the image guidance has made it extremely attractive and easy to do.

I wanted to give you a brief overview of what we do here at San Diego that is a bit unique. My name is Kevin Murphy, here at UCSD. Thank you.


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