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Current Management of Childhood Ependymoma

Current Management of Childhood Ependymoma

Dr. Merchant provides a comprehensive overview of
intracranial ependymoma in children. As he points out, most of the current
information regarding childhood intracranial ependymoma has come from
single-institution retrospective reviews. Of the prognostic indicators mentioned
in the article, both young age and subtotal resection are widely accepted.
Children less than 3 years old have a worse prognosis than older children,
possibly because of more aggressive tumor biology, reluctance to give
postoperative radiotherapy, or use of lower doses of radiotherapy. Regarding the
degree of surgical resection, assessment by postoperative imaging is more
important than the neurosurgeon’s perspective on whether a gross total or
subtotal resection has been performed.[1,2]

Tumor grade is a controversial prognostic factor. Our experience and that of
others indicate a worse outcome for high-grade or anaplastic ependymomas[3,4];
however, cooperative group studies and other single-institution reviews have not
verified this finding.[2,5] One problem concerning tumor grade is the lack of
agreement among individual pathologists. In a study from the Children’s Cancer
Group, 22 (69%) of 32 cases had a discrepancy in the diagnosis on central
review.[2]

Radiotherapy Volume

Perhaps one of the more controversial topics in ependymoma until recently has
been the volume of irradiation. Studies from the 1970s to early 1980s reported a
better outcome among patients receiving wide-field irradiation (craniospinal and
whole-brain radiotherapy).[6] With the advent of better imaging and surgical
techniques, current evidence indicates that the predominant pattern of failure
is local, regardless of tumor grade or location.[2-3,5] For infratentorial
ependymomas, the entire posterior fossa does not need to be treated.[7]

Our current recommendation for a nondisseminated ependymoma is local
radiotherapy. Craniospinal irradiation has more toxicity and may protract
treatment duration, which can affect eventual outcome.[8,9] Craniospinal
radiotherapy is reserved for the less than 10% of children with neuraxis
dissemination.

Radiotherapy Dose

Studies that have shown a dose response level for ependymoma indicate a dose
threshold of 45 to 50 Gy.[10,11] More recent studies suggest that
dose escalation in subtotally resected tumors may be beneficial. As Dr.
Merchant correctly points out, the Pediatric Oncology Group (POG) study 9132
used hyperfractionated radiotherapy to a total dose of 69.6 Gy (1.2 Gy twice
daily). The 4-year event-free survival rate was 50%, compared to 24% in an
earlier POG study that used a lower total dose of conventional radiotherapy.[12]

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