Patterns of failure using a conformal radiation therapy tumor bed boost for medulloblastoma.
OBJECTIVE
To assess the patterns of failure for patients with medulloblastoma receiving a conformal tumor bed boost rather than a boost to the entire posterior fossa.


METHODS
From 1994 to 2002, 32 consecutive patients with newly diagnosed medulloblastoma treated at Memorial Sloan-Kettering Cancer Center (New York, NY) received a conformal boost to the tumor bed in conjunction with craniospinal radiation therapy. Twenty-eight patients also received chemotherapy. The median age was 9 years (range, 3 to 34 years), and the male to female ratio was 3:1. Twenty-seven patients had standard-risk disease, and five patients had high-risk disease. Craniospinal doses ranged from 23.4 to 39.6 Gy, and total tumor bed doses ranged from 54 to 59.4 Gy.


RESULTS
With a median follow-up of 56 months, six patients have relapsed; five relapsed outside of the posterior fossa, and one failed within the posterior fossa, outside of the high-dose boost volume. Five-year actuarial disease-free and overall survival rates were 84% and 85%, respectively. Freedom from posterior fossa failure was 100% and 86% at 5 and 10 years, respectively. Freedom from distant failure was 84% at 5 years, with a trend for improvement when full-dose craniospinal radiation (36 to 39.6 Gy) was used compared with a reduced dose (23.4 Gy) of radiation (100% v 63%, respectively; P =.06). No other predictive variables were identified.


CONCLUSIONS
Conformal treatment to the tumor bed allows for significant sparing of critical structures. The posterior fossa failure rate in this series is similar to that reported when the entire posterior fossa is treated. This approach should be investigated further in a phase III trial.
Wolden
Suzanne L
SL
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, Box 22, New York, NY 10021, USA. woldens@mskcc.org
Dunkel
Ira J
IJ
Souweidane
Mark M
MM
Happersett
Laura
L
Khakoo
Yasmin
Y
Schupak
Karen
K
Lyden
David
D
Leibel
Steven A
SA
D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001932:Brain Neoplasms / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000628:therapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*