Low early ototoxicity rates for pediatric medulloblastoma patients treated with proton radiotherapy
1 Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
2 Texas Children's Cancer Center, Baylor College of Medicine, Houston, TX, USA
3 Department of Radiation Oncology, University of Louisville, Louisville, KY, USA
4 Department of Head and Neck Surgery, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
5 Department of Pediatrics, University of Texas M.D. Anderson Cancer Center, Houston, TX, USA
Radiation Oncology 2011, 6:58 doi:10.1186/1748-717X-6-58Published: 2 June 2011
Hearing loss is common following chemoradiotherapy for children with medulloblastoma. Compared to photons, proton radiotherapy reduces radiation dose to the cochlea for these patients. Here we examine whether this dosimetric advantage leads to a clinical benefit in audiometric outcomes.
From 2006-2009, 23 children treated with proton radiotherapy for medulloblastoma were enrolled on a prospective observational study, through which they underwent pre- and 1 year post-radiotherapy pure-tone audiometric testing. Ears with moderate to severe hearing loss prior to therapy were censored, leaving 35 ears in 19 patients available for analysis.
The predicted mean cochlear radiation dose was 30 60Co-Gy Equivalents (range 19-43), and the mean cumulative cisplatin dose was 303 mg/m2 (range 298-330). Hearing sensitivity significantly declined following radiotherapy across all frequencies analyzed (P < 0.05). There was partial sparing of mean post-radiation hearing thresholds at low-to-midrange frequencies and, consequently, the rate of high-grade (grade 3 or 4) ototoxicity at 1 year was favorable (5%). Ototoxicity did not correlate with predicted dose to the auditory apparatus for proton-treated patients, potentially reflecting a lower-limit threshold for radiation effect on the cochlea.
Rates of high-grade early post-radiation ototoxicity following proton radiotherapy for pediatric medulloblastoma are low. Preservation of hearing in the audible speech range, as observed here, may improve both quality of life and cognitive functioning for these patients.