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    Spotlight on Conformal Radiation

    It’s premiere night. The red carpet is out, and the star of the show—radiation therapy—is making its comeback performance.

    Often thought to be a character with a dark side, radiation therapy has been revived in a new and improved form. Conformal radiation therapy is now taking center stage. In a recent study at St. Jude Children’s Research Hospital, conformal radiation received rave reviews. When used on children with ependymoma—a malignant brain tumor—this treatment allowed patients to have normal development of memory, reasoning, problem-solving and other cognitive functions.

    In the spotlight

    What makes conformal radiation so revolutionary? This precise treatment sends radiation beams from several directions directly onto the brain tumor, killing it and sparing the rest of the brain from harmful effects of radiation.

    The therapy combines CAT scans and MRI to create pictures of the cancer that a computer then turns into three-dimensional images of the tumor exactly as it appears in the brain. These images are combined with computer-controlled radiation beams and meticulous positioning of the patient’s treatment table. Radiation hits the tumor at precisely calculated angles and depths matching the 3-D image of the tumor, obliterating the cancer and sparing healthy tissue.

    “Radiation is the most effective agent in the treatment of pediatric brain tumors,” says Thomas Merchant, DO, PhD, chief of Radiation Oncology and principal investigator for a report on the study that appeared in the August 2004 Journal of Clinical Oncology. “However, the advantages of radiation therapy are partly offset by the potential side effects, which range in severity and importance. Radiation may have devastating consequences to neurological, cognitive and hormonal systems affecting growth and development.”

    Oncologists have long recognized the powerful effect of radiation in eradicating tumors but have often tried to delay or avoid radiation by using surgery or higher doses of chemotherapy. With new advances in the world of radiation, many treating physicians welcome the reintroduction of radiation as a front-line treatment.

    Results of the St. Jude study hold promise for sparing cognitive development even in extremely young children. Forty-eight of the 88 patients in the St. Jude study were under 3 years of age at the time of irradiation. Including children in that age bracket was a unique aspect of the study, since those patients are at greatest risk to suffer radiation side effects.

    “Our recent trials have been designed to reduce the volume of irradiation,” Merchant says. “Most encouraging has been a reduction in side effects in many of the younger children for whom radiation therapy has been avoided for nearly two decades.”

    Investigators found that tumor control was successful for about 75 percent of the children with ependymoma. In previously reported studies, radiation therapy had enjoyed a success rate of only 50-60 percent.

    “The improved outcomes we have seen in both disease control and intellectual development using conformal radiation therapy suggest it might be possible to reintroduce the routine use of radiation therapy as a treatment option even for very young children,” Merchant says.

    On target

    Louis Hentz is one child who hopes to benefit from conformal radiation therapy. Last April, during a routine checkup, doctors found that the 1-year-old had the brain tumor medulloblastoma. After undergoing surgery in Ohio to remove the tumor, Louis’ parents, Mike and Kerin, began researching protocols, hospitals and ways to reduce the risk of Louis’ tumor returning.

    “In this whole process, we had the biggest fear of radiation, but we armed ourselves with a lot of research,” recalls Mike. “We had several hospitals in mind with protocols we felt would be effective for Louis’ tumor, but we weren’t sure about radiation.”

    The parents read about the long-term side effects of radiation and were told by some physicians to avoid the treatment. The Hentzes learned that most children with medulloblastoma have recurrences if they do not receive radiation therapy. “We thought that was too high of a risk,” recalls Mike.

    “We chose to bring Louis to St. Jude because we felt this hospital had more experience than anybody else in dealing with such young children with brain tumors,” he continues.

    At St. Jude, physicians treat medulloblastoma with conformal radiation therapy in addition to surgery and chemotherapy. Children with medulloblastoma under the age of 3 undergo a different kind of conformal radiation therapy than do patients with ependymoma. Kids with medulloblastoma receive treatment to the posterior fossa portion of the brain for two weeks; then treatment is limited to the tumor bed for three to four weeks.

    In Memphis, scans showed that Louis’ tumor was not completely gone, and he underwent another operation. “The tumor was much larger than the scans in Ohio had shown,” Mike says. “I’m glad Louis had another surgery so we could start with zero tumor.”

    When Mike and Kerin read a July 2004 U.S. News & World Report story about conformal radiation therapy at St. Jude, they knew they had come to the best place. “That was a nice reinforcement that conformal radiation was the right route for us,” he says.

    Now starring

    St. Jude is currently the world’s leader in the field of pediatric neuroradiotherapy.

    “From a treatment standpoint, there is no better place for radiation therapy because we treat more children than any other facility in the country,” Merchant says. “Our results are used in the clinical trial designs for national and international studies. Our knowledge of radiation-related side effects expanded markedly with the results from our recent trials.

    "We also have the largest team of radiation oncologists devoted uniquely to pediatric radiation oncology.”

    Merchant attributes the encouraging results from the study to three factors: the large number of patients who underwent extensive surgery to remove most of their tumors before irradiation; the use of conformal radiation therapy to target tumors; and the relatively high dose of radiation that could be used without jeopardizing healthy brain tissue.

    St. Jude will continue pushing the envelope of radiation and enhancing its brain tumor program with the addition of a new Integrated Patient Care and Research Building. The hospital broke ground for the 300,000-square-foot facility in August of 2004.

    “The new facilities and equipment will enhance our ability to treat patients with brain tumors and will give us the opportunity to dedicate a room to one of the newer treatment devices under development that will take conformal radiation to the next level,” Merchant says.

    As for Louis, he is handling treatment well. “The nice part of this treatment for him is that the younger kids get to go first,” Mike says. “So, it’s early mornings of sedation, 30 minutes of radiation and about 20 minutes of waking up from treatment.

    “After treatment he’s a little grumpy at first, but he hasn’t had much anxiety about it because he’s so young,” Mike continues. “We will never be totally comfortable with radiation, but we know it’s the best option for him, and St. Jude is the best hospital for it.”

    Reprinted from Promise magazine, winter 2005


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