ID #1164 Sodium thiosulphate use in children with medulloblastoma, more important in a limited resource country?

Background Cisplatin-induced sensorineural hearing loss (CI-SNHL) is a significant complication of pediatric cancer treatment, with potential long-term impacts on the academic and social development. Sodium thiosulfate (STS) has been approved for the prevention of CI-SNHL in patients with non-metastatic solid tumors. Methods We retrospectively reviewed the medical charts of children diagnosed with medulloblastoma and used STS at KHCC/Jordan. All patients had regular hearing assessments. We reviewed patients’ characteristics, treatment received and audiograms’ results. Results Twenty-nine patients were identified (F:M 1.2); with a median age of 8.9 years (range, 5-16.3 years). Histology was classic (18) , anaplastic (10) and desmoplastic (1). Molecular subgrouping revealed: Wnt (10), G4(8), SHH (4, 2 were TP53+), G3 (3), G3/4 (3), and one was not tested. Five patients had residual tumor >1.5cm2 but all tumors were M0. Patients received concurrent weekly VCR with radiotherapy (5 received 36-39.6 Gy CSI). One patient with G3 medulloblastoma received daily carboplatin. Patients were treated as per ACNS0332 protocol; 173 of the 174 planned cisplatin doses were given (15 were dose reduced). The median cumulative cisplatin dose was 450mg/m2 (range,356-450mg/m2). At the end of therapy, 19 (66%) of patients had no ototoxicity; all received 450mg/m2 cumulative cisplatin dose. Six patients had grade 1 ototoxicity, three grade 2 and one grade 3. STS was well tolerated. Twenty-six patients (90%) are alive at a median follow up of 3.1 years (range, 2.2- 5.9 years), one of them is receiving chemotherapy following relapse. Three patients died after relapse: one with TP53+SHH, one with G4 and one with Wnt. Conclusions STS administration in this small cohort of non-metastatic medulloblastoma was feasible and seemed to help decrease CI-SNHL. This experience shows that STS can potentially have a major impact in countries with limited resources. Longer follow up is needed to assess its safety on tumor control.