PATH-01. H3K27M Mutation: A Predictor of Intracranial Metastasis in Patients Undergoing Surgical Resection of Intramedullary Spinal AstrocytomasRunning HeadH3K27M as a predictor of intracranial metastasis

Abstract OBJECTIVE H3 K27M-mutant tumors are uncommon and rare presentations which make their management delayed, cumbersome and confusing. The aim of this study was to establish the association of H3K27 mutation with outcomes in patients undergoing surgical resection of Spinal astrocytomas (SA). METHODS All patients with a follow up of at least 12 months undergoing resection of SA were included in this study between the years 2016 to 2021. Specimens of resected SA were tested in the neuropathology lab. Immunohistochemistry with the corresponding antibodies was used to evaluate the H3K27M-mutant status. The patients’ clinical outcome was measured using Modified McCormick scale (MMS) while MRI was used for surgical outcomes. RESULTS 71 patients with a mean age of 33.07yrs were included in the study. Twelve patients (17%) had H3K27M mutation. There was no significant difference in the MMS immediately postoperatively (p=0.725), at discharge (p=1.000) or at last month follow-up (p=0.354) between the patients with and without H3K27 mutations. Though the patients with and without the mutation had comparable recurrence and residual rates, the rate of intracranial metastasis was significantly higher in patients with H3K27 mutation (42% vs 1.7%, p=0.003). There was a significant difference in the median overall survival of the two groups (72 months vs 15 months, p<0.001) CONCLUSION Patients with H3K27 mutation must be managed with a holistic approach consisting of aggressive treatment options to avoid intracranial metastasis and improve their survival rates.