Intensity-modulated radiation therapy for pediatric medulloblastoma: early report on the reduction of ototoxicity.
OBJECTIVE
The combination of cisplatin chemotherapy and radiation therapy for the treatment of medulloblastoma has been shown to cause significant ototoxicity, impairing a child's cognitive function and quality of life. Our purpose is to determine whether the new conformal technique of intensity-modulated radiation therapy (IMRT) can achieve lower rates of hearing loss by decreasing the radiation dose delivered to the cochlea and eighth cranial nerve (auditory apparatus).


METHODS
Twenty-six pediatric patients treated for medulloblastoma were retrospectively divided into two groups that received either conventional radiotherapy (Conventional-RT Group) or IMRT (IMRT Group). One hundred thirteen pure-tone audiograms were evaluated retrospectively, and hearing function was graded on a scale of 0 to 4 according to the Pediatric Oncology Group's toxicity criteria. Statistical analysis comparing the rates of ototoxicity was performed using Fisher's exact test with two-tailed analysis.


RESULTS
When compared to conventional radiotherapy, IMRT delivered 68% of the radiation dose to the auditory apparatus (mean dose: 36.7 vs. 54.2 Gy). Audiometric evaluation showed that mean decibel hearing thresholds of the IMRT Group were lower at every frequency compared to those of the Conventional-RT Group, despite having higher cumulative doses of cisplatin. The overall incidence of ototoxicity was lower in the IMRT Group. Thirteen percent of the IMRT Group had Grade 3 or 4 hearing loss, compared to 64% of the Conventional-RT Group (p < 0.014).


CONCLUSIONS
The conformal technique of IMRT delivered much lower doses of radiation to the auditory apparatus, while still delivering full doses to the desired target volume. Our findings suggest that, despite higher doses of cisplatin, and despite radiotherapy before cisplatin therapy, treatment with IMRT can achieve a lower rate of hearing loss.
Huang
Eugene
E
Department of Radiology/Section of Radiation Oncology, Baylor College of Medicine, Houston, TX, USA.
Teh
Bin S
BS
Strother
Douglas R
DR
Davis
Quillin G
QG
Chiu
J Kam
JK
Lu
Hsin H
HH
Carpenter
L Steven
LS
Mai
Wei Yuan
WY
Chintagumpala
Murali M
MM
South
Michael
M
Grant
Walter H
WH
Butler
E Brian
EB
Woo
Shiao Y
SY
D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001299:Audiometry; D002528:Cerebellar Neoplasms / Q000188:drug therapy / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D005260:Female; D006309:Hearing / Q000528:radiation effects*; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000188:drug therapy / Q000532:radiotherapy*; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D012189:Retrospective Studies