RONC-05. PRESERVING VISION IN OPTIC PATHWAY GLIOMA AMONG PATIENTS WITHOUT NEUROFIBROMATOSIS TYPE 1

PURPOSE: Sporadic optic pathway/hypothalamic gliomas (OP/HGs) represent a unique entity within pediatric low-grade glioma. Despite favorable survival, the location makes treatment difficult and local progression debilitating. We conducted longitudinal assessment of visual acuity (VA) among patients treated in the modern era with chemotherapy (CT) or early radiotherapy (RT). METHODS: Clinical characteristics were abstracted for patients treated over a 15-year period (2000–2015) at a single institution. Comprehensive ophthalmologic data taken at three to six-month intervals was examined with age-appropriate VA metrics converted to LogMAR scale. Kaplan-Meir “blindness-free survival” (BFS) curves were calculated as time to bilateral functional blindness (i.e. LogMAR ≥ 0.8 in both eyes), stratified by treatment and compared using log-rank test. RESULTS: Thirty-six patients with median follow-up of 7.6 years (range: 2–17) were identified. Median age at diagnosis was 2.5 years (IQR: <1–5). Early RT was administered as initial therapy (n=6) or first-line salvage (n=5) in a total of eleven patients (31%) at a mean age of 12 years (range: 6–17). Twenty-five patients (69%) were maintained primarily on CT with a mean age at initiation of 2.4 years (range <1–8). Of these, five patients received RT after ≥2 systemic therapy regimens. In terms of visual preservation, five/eight-year BFS rates were 84%/59% and 100%/100%, for CT and early RT, respectively (p=0.046). CONCLUSIONS: In a contemporary cohort, early RT, defined as initial or 1(st) line salvage therapy for OP/HGs manifested in superior VA. Children undergoing CT are at highest risk of functional blindness following five years of treatment.