medwireNews: The risk of high-frequency hearing loss (HL) in children undergoing cancer treatment to the central nervous system (CNS) or the head and neck could be reduced by minimising doses of radiation to the cochlea and limiting cumulative doses of cisplatin or carboplatin, Canadian researchers say.
“Our findings can identify children for whom early intervention with assistive devices and neurocognitive evaluation should be sought”, write Derek Tsang, from the Princess Margaret Cancer Center in Toronto, Ontario, and co-workers in the Journal of Clinical Oncology.
“Efforts should be made to spare the cochlea during [radiotherapy] planning, when possible, without compromising tumor coverage”, they recommend.
The team examined for HL in 340 ears of 171 children who were treated for CNS or head and neck tumours between 2005 and 2017.
Multivariable weighted regression analysis showed that increasing levels of HL, based on International Society of Pediatric Oncology–Boston grade, were significantly predicted by an increase in average radiation dose to the cochlea (odds ratio [OR]=1.04 per Gy), and with increasing doses of cisplatin (OR=1.48 per 100 mg/m2) and carboplatin (OR=1.41 per 1000 mg/m2).
The researchers report “a rapid onset of high-frequency HL after early treatment exposures, followed by a delayed onset of medium- and low-frequency HL over time”.
They also report the “striking finding” that 5 years after completing radiotherapy, there was a 50% or greater incidence of high frequency HL, above 4 kHz, when patients had received a mean cochlea dose of over 30 Gy of radiation, and the risk of HL at all frequencies continued to increase for more than 5 years.
And the investigators emphasize that “[p]atients who received any platinum-based chemotherapy were at markedly elevated risk of high-frequency HL, particularly if mean cochlea doses were > 20 Gy”, as were children who were younger than 3 years of age at the time of radiotherapy, “even with modest doses”.
However, Tsang et al note that the effect of combination treatment with radiotherapy and chemotherapy had an additive but not synergistic effect on HL.
“We propose a mean cochlea dose of 30 Gy as an aspirational threshold to minimize the risk of HL. In patients receiving chemotherapy, a lower threshold (20-25 Gy) may be considered to minimize the cumulative ototoxic burden”, they write.
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This independent news story was supported by an educational grant from L’Institut Servier, Suresnes, France.