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    Thomas E. Merchant, DO, PhD

    Better therapy with less radiation

    St. Jude investigators have demonstrated how to treat locally aggressive brain tumors called craniopharyngiomas by exposing the least amount of brain volume to radiation while still getting maximum therapeutic benefit. The finding is important because the treatment reduces the potential for damaging healthy brain tissue in an attempt to eliminate the tumor.

    A report on this work appears in the February 2006 issue of the Journal of Neurosurgery: Pediatrics (Supplement 2).

    The St. Jude team used conformal radiation therapy (CRT) to treat the tumors while reducing the margin (tissue surrounding the tumor) that was exposed to radiation from 2 cm to 1 cm. CRT combines CAT scans and MRI to create pictures that a computer turns into 3-D images of the tumor exactly as it appears in the brain. Using these images, computer-controlled radiation beams and meticulous positioning, radiation hits the tumor from precisely calculated angles and depths, destroying the cancer and sparing healthy tissue. This was the first study of its type in the nation to include craniopharyngioma.

    The investigators followed 28 patients after CRT for 24 to 80 months and found that 90 percent of them experienced no tumor progression. The study also showed that children younger than 7.4 years at treatment time were at higher risk for suffering reduced cognitive development. Other factors adversely affecting cognitive development were a delay of more than 73 days between diagnosis of the tumor and treatment, having hydrocephalus (abnormal accumulation of cerebrospinal fluid in the brain cavities called ventricles) and having had multiple surgeries to treat the tumor.

    “Analysis of the outcome of this treatment in children will help us better understand the effects of radiation therapy,” said Robert Sanford, MD, an adjunct in Radiological Sciences. Sanford is senior author of the paper.

    “Although the outcome was promising, we still need to develop ways to further reduce radiation exposure to limit its effects on cognitive development,” added Thomas Merchant, DO, PhD, Radiological Sciences, principal investigator and lead author.

    The paper’s other St. Jude authors include Larry Kun, MD, Radiological Sciences chair; the late Raymond Mulhern, PhD, former Behavioral Medicine chief; and Chenghong Li, Biostatistics.


    Last update: June 2006