RONC-08. Validation of Online Calculator for Estimating Severe Hearing Loss Risk Among Patients with Medulloblastoma After Receiving Photon Radiation and Cisplatin Chemotherapy

BACKGROUND: Children with medulloblastoma are at risk of hearing loss (HL) following cranial radiotherapy and platinum-based chemotherapy. Keilty et al. 2021. J Clin Oncol. (PMID: 34570616) recently published a computer-based HL risk calculator based on children with central nervous system tumors treated with photon radiotherapy. The objective of this study was to evaluate the performance of the risk calculator in an independent cohort of children with medulloblastoma treated with photon radiotherapy. METHODS: We identified children with medulloblastoma treated with cisplatin and photon radiotherapy at Texas Children’s Hospital between 1997-2007. Audiograms were graded using the International Society of Pediatric Oncology-Boston scale (SIOP-Boston). The risk calculator considered age at treatment, time since radiotherapy, cumulative cisplatin dose (mg/m2), and cochlea radiation dose (Gy). The calculated risk was compared between ears with and without clinical evidence of grades 3/4 HL using t-test. RESULTS: We identified 45 eligible patients (male: 31, female: 14) diagnosed at a median age of nine years (range: 3-18 years). The mean cochlea dose was 37.2 Gy (range: 25.2-54.9 Gy) and mean cumulative cisplatin dose was 352 mg/m2 (range: 55-860 mg/m2). Audiograms of 89 total ears were available with a median follow-up of 65 months post-diagnosis (range: 13-163 months). The median number of post-radiotherapy audiograms per patient was 6 (range: 2-15). A total of 22 ears (25%) belonging to 13 individual patients (29%) met the SIOP-Boston criteria for grades 3/4 HL. The mean of predicted probability of severe HL based on the calculator for ears with SIOP-Boston grades 3/4 was 24% (range: 10% - 48%) compared to 32% (range: 10%-70%) among ears with grades < 3 HL. CONCLUSION: The published HL risk calculator did not clearly differentiate between patients with and without clinically significant HL in our cohort. Future multicenter studies are required to validate this tool and improve the prognostic potential.³