CTNI-56. A MULTI-INSTITUTIONAL RETROSPECTIVE SERIES OF ADULT-ONSET MEDULLOBLASTOMA

Abstract Adult-onset medulloblastoma is a rare tumor for which limited data exists. Current treatment based on from childhood medulloblastoma. We present retrospective cohort of 130 consecutive patients age ≥ 18 years and treated at the University Washington (N = 61), Florida 50), Stanford 19), 2000-2021. Median duration follow-up was 57.3 months. Patients were 57.7% male (75/130), with median diagnosis 29 years. 5 10-year overall survival 78.9% 67.6% no recurrence seen beyond 10 31/130 (23.8%) had Chang M1 or greater disease molecular typing available 41/130 patients. There improvement in progression-free (PFS) (OS) either who received proton therapy those concurrent vincristine. trend favoring longer OS receiving radiotherapy within 6 weeks surgery. A towards shorter higher craniospinal radiation dose ( > 30Gy) likely reflected accurate clinical risk stratification. PFS adjuvant chemotherapy overall, but cycles improved (HR 2.10, 95% CI 1.19 - 3.90, p 0.038) to 2.07, 95%CI 0.81-5.25, 0.125). After first progression, 20.7 months both 24.8%. conclude that surveillance past may be unnecessary 1 4 achieve long-term after relapse. Within confines study, these suggest equivalence between photon radiotherapy, benefit vincristine, least are required delay progression.