MBCL-47. OTOTOXICITY IN MEDULLOBLASTOMA SURVIVORS FOLLOWING PROTON RADIATION

ABSTRACT: Abstract BACKGROUND Radiotherapy to the cochlea and cisplatin exposure are both associated with hearing loss (HL) in medulloblastoma survivors. Here we report late outcomes in survivors with ?1 year audiogram testing. METHODS Prospective medulloblastoma trial participants (clinicaltrials.gov: NCT01063114/NCT00105560) with ?1 years of audiogram follow-up (FU, n=110 pts) comprised the study cohort. HL was graded using the SIOP-Boston ototoxicity scales (0-4) for each ear. Associations between grade 3 HL and mean cochlear radiation dose and cumulative cisplatin dose were evaluated. Target cisplatin dose was 450 mg/m2 but most patients did not receive full dose as dose reductions were used when ototoxicity was detected during chemotherapy. FINDINGS Median follow-up was 4.0 years (range 1-10). At baseline, 10 ears (4.5%) had grade 3 HL. At latest FU, an additional 49 ears developed grade 3 HL (23.3%). There was no grade 4 HL. Median average cochlear dose across both ears was 29.9 Gy (20.8-50.6) and median cisplatin dose was 375.0 mg/m2 (60.0-583.0). Mean cochlear radiation dose for grade 3 HL (n=56) was 32.5Gy (24.1-47.0), compared with 31.8Gy (20.8-50.6, p=0.19). Mean cisplatin dose for grade 3 HL was 347.3mg/m2 (180.0-450.0), compared with 374.2mg/m2 for grade 0-2 ears (60.0-583.0, p=0.05). INTERPRETATION Significant hearing deficits (SIOP-Boston grade 3) develop in approximately 23.3% of medulloblastoma patients. In this cohort, higher mean radiation dose did not affect HL rates. The lower mean cumulative cisplatin dose in pts with grade 3 HL suggests cisplatin ototoxicity is driving HL, and that host susceptibility may play a role.

SUBMITTER: Byun J 

PROVIDER: S-EPMC6012575 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature