paediatrics Brussels 17

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INVITED PAPER
Three-dimensional conformal radiation therapy
for ependymoma
Thomas E. Merchant
Received: 26 March 2009
# Springer-Verlag 2009
Abstract
Introduction The application of conformal radiation thera-
py in the treatment of pediatric ependymoma is a success
story resulting from advances in radiation therapy planning
and delivery. These advances occurred at a time when
clinical trial results confirmed that radiotherapy avoidance
strategies were unsuccessful.
Discussion Investigators have been keen to confirm the
promise of newer radiation therapy methods even for the
youngest children. When preliminary results suggested that
high-dose focal irradiation could be safely administered
through systematic targeting and that cognitive function
could be preserved, investigators moved to include confor-
mal therapy in the frontline management of children
regardless of age. The results with postoperative conformal
radiation therapy were further enhanced when neurosur-
geons increased the rate of gross-total resection and
recognized that second surgery could be safely accomplished
after incomplete initial resection. With more than a decade of
experience, the role of conformal radiation therapy in the
treatment of childhood ependymoma has been firmly
established as investigators consider new trials to increase
disease control and improve functional outcomes.
Keywords Radiation therapy . Pediatrics . Ependymoma .
Brain tumor
Purpose
Ependymoma describes a diverse group of central nervous
system (CNS) tumors for which the very young are
disproportionably represented; nearly half of pediatric cases
occur in children under the age of 4 years ]. The factor of
age is a critical point for successful treatment of ependy-
moma that requires aggressive surgery and high-dose
postoperative radiation therapy. Incomplete resection and
high rates of local failure characterize past institutional and
cooperative group series for older children ]. When
radiation therapy avoidance was the hallmark of clinical
trials for younger children, results were inferior to those
achieved when radiation therapy was administered as a part
of frontline management ].
Two decades ago, radiation therapy for ependymoma
consisted of craniospinal irradiation with or without
chemotherapy. Long-term event-free survival was less than
40% ]. Patients experienced tumor progression at the
primary site because most had measurable residual tumor at
the time of irradiation. Because of concern about neuraxis
dissemination, especially in patients with high-grade
tumors, craniospinal and boost irradiation of the primary
site was administered postoperatively. Those who survived
suffered debilitating side effects. Recognition that primary
site irradiation was equivalent to craniospinal irradiation
occurred at a time when radiotherapy avoidance was
becoming the regimen of choice for younger patients and
the advantage of focal treatment, even using conventional
techniques, could not be realized because of the persistently
high rates of local failure ].
Three-dimensional conformal radiation therapy trials
were developed in the early 1990s at major medical centers
in the USA. Supported by government contracts, these trials
showed that radiation dose to prostate, head and neck, and
Childs Nerv Syst
DOI 10.1007/s00381-009-0892-9
T. E. Merchant (*)
Department of Radiological Sciences, Mail Stop 220,
St. Jude Children’s Research Hospital,
262 Danny Thomas Place,
Memphis, TN 38105-3678, USA
e-mail: