OTHR-40. DICER 1- a rare , but important tumor driver in malignant progressive brain tumors

BACKGROUND: DICER mutation is a known tumor driver involved in pleuropulmonary blastoma ,renal tumors, masses in the thyroid and ovary and multiple other manifestations. Brain tumors are considered to be a rare manifestation of germline DICER mutation. Currently, brain imaging is not included in the standard follow up of patients with DICER germline mutation, and data re the prevalence of somatic DICER mutations in brain tumors is limited. AIMs: evaluation of prevalence of DICER mutations in a large cohort of rare/relapsed brain tumors. METHODS: over the last year all patients with tumors lacking curative standard therapy in Israel were sent for next generation sequencing,. Molecular evaluation was done using either panel based evaluation (ONCOMINE/Foundation) or whole exome and whole transcriptome (INFORM consortium). Epidemiological data as well as clinical outcome were provided by the treating physician. RESULTS: Between April 2021 and January 2022 one hundred twenty nine samples were sent for molecular analysis, 58 of them were brain tumors. Six patients had DICER associated malignant tumors , 33% of them were brain tumors . One patient with pinealoblastoma was diagnosed with a highly metastatic disease associated with a very grave prognosis. CONCLUSION: brain tumors are an important group among malignant DICER associated tumors. Surveillance may lead to early detection which may be associated with a better outcome.