LG-51: RETROSPECTIVE ANALYSIS OF PATHOLOGICALLY DIAGNOSED LOW-GRADE GLIOMA: EXPERIENCE OF A SINGLE INSTITUTE

BACKGROUND: Low-grade gliomas (LGGs) are heterogeneous tumors and optimal management has not yet been established. OBJECTIVE AND METHODS: For better understanding of pediatric LGG, we retrospectively analyzed pathologically-confirmed cases of LGGs in our institute between 1995 and 2015. RESULTS: Forty-five cases were included. Median age at diagnosis was 5 years. The most frequent pathological subtype was PA (n = 24), followed by DA (n = 8) and PXA (n = 3). Main tumor locations were cerebellum (n = 13) and cerebral cortex (n = 12). Twenty-one patients underwent GTR and among twenty-four patients with non-GTR, 20 patients received CTx and 9 received RT (seven received both). Forty-three patients were alive and two patients showed malignant transformation (MT) and died of disease. OS at 5 and 10 years was 100% and 92% and PFS at 3, 5 and 10 years were 81%, 65% and 61%.respectively. GTR had positive impact on PFS. Retrospective molecular analysis of 42 cases revealed V600E mutation in 6 cases including PXA (n = 2), DA (n = 2), OA and PA, and KIAA-BRAF fusion in 14 cases including PA (n = 13). FGFR mutations were detected from initial biopsy samples of two of two MT cases including optic PA and thalamic DA. H3F3.K27 mutation was detected in two cases including thalamic DA that showed MT and supratentorial OA. In the latter case, the patient underwent GTR and alive in CR for 5 years. CONCLUSION: Although the overall survival of LGGs is excellent, some patients with non-GTR LGG showed relapse for years after treatment. Presence of specific mutation may be the predictor of MT.