Reducing toxicity from craniospinal irradiation: using proton beams to treat medulloblastoma in young children.
OBJECTIVE
We report on a radiation treatment technique that has reduced the dose to critical normal structures in children with medulloblastoma.


METHODS
Three children between the ages of 3 and 4 with stage M2 or M3 medulloblastoma were treated between 2001 and 2003 with craniospinal irradiation using protons. Patients received 36 cobalt gray equivalent to the craniospinal axis, then 18 cobalt gray equivalent to the posterior fossa. The cranium was treated with opposed lateral fields. The spine was treated with three matched posteroanterior fields, with the beam stopping just beyond the thecal sac. The posterior fossa was then treated with alternating posteroanterior, right posterior oblique, and left posterior oblique fields, with the beam stopping just proximal to the cochlea. The use of general anesthesia and pre-porting with diagnostic-quality x-rays allowed precise patient positioning.


RESULTS
Craniospinal irradiation delivered via conformal proton irradiation substantially reduced the dose to the cochlea and vertebral bodies and virtually eliminated the exit dose through thorax, abdomen, and pelvis. Despite concurrent chemotherapy, a clinically significant lymphocyte count reduction was not seen. Patients tolerated treatment well; acute side effects (e.g., nausea, decreased appetite, and odynophagia) were mild. All patients completed therapy without interruption.


CONCLUSIONS
Our proton-beam technique for craniospinal irradiation of pediatric medulloblastoma has successfully reduced normal-tissue doses and acute treatment-related sequelae. This technique may be especially advantageous in children with a history of myelosuppression, who might not other wise tolerate irradiation.
Yuh
Grace E
GE
Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California 92354, USA.
Loredo
Lilia N
LN
Yonemoto
Leslie T
LT
Bush
David A
DA
Shahnazi
Kambiz
K
Preston
William
W
Slater
James M
JM
Slater
Jerry D
JD
D002528:Cerebellar Neoplasms / Q000532:radiotherapy*; D002675:Child, Preschool; D016371:Cranial Irradiation / Q000379:methods; D005260:Female; D006801:Humans; D018655:Lymphocyte Count; D008527:Medulloblastoma / Q000532:radiotherapy*; D010865:Pilot Projects; D061766:Proton Therapy; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods; D013116:Spinal Cord / Q000528:radiation effects; D016896:Treatment Outcome; D011522:Protons
D011522:Protons