PT-06 * RANDOMIZED TRIAL OF HIGH-PRECISION CONFORMAL RADIATION THERAPY COMPARED TO CONVENTIONAL RADIOTHERAPY IN PRESERVATION OF LONG-TERM NEURO-COGNITIVE OUTCOMES IN YOUNG PATIENTS WITH PROGRESSIVE OR RESIDUAL BENIGN/LOW-GRADE BRAIN TUMORS

BACKGROUND: To report neuro-psychological outcomes in young patients with progressive benign and low-grade brain tumors treated with high-precision stereotactic conformal radiotherapy (SCRT) versus conventional radiotherapy (Conv RT) (NCT00517959). METHODS: Between 2001-10, 200 patients (median age 13 years, commonest histology craniopraryngioma) were randomized to SCRT (n = 105; 6MV, non-coplanar fields using micromultileaf collimators) or Conv RT (n = 95; 6MV, 2-4 open fields) to 54 Gy/30 fractions. Neuropsychological battery included full-scale IQ (FSIQ), verbal quotient (VQ), performance quotient (PQ), memory quotient (MQ in patients > 16 years) by Wechsler scores, LOTCA battery and state-trait Anxiety Inventory and Hamilton Anxiety-Depression Scales. Serial evaluations were performed at baseline (pre-RT), 6-months and 2, 3, 4, and 5-years post-RT and analyzed using generalized linear-mixed model (GLMM). RESULTS: Pre- RT baseline revealed considerable proportion of patients with low intelligence in both arms indicating effects of tumor and prior treatments. GLMM for repeated measures demonstrated significantly better preservation of FSIQ over time in SCRT versus Conv RT arm at 3 years (p = 0.0003) and 5 years (p = 0.012). There was significantly better preservation of VQ (age < 16 years) (p = 0.047) and MQ (age > 16 years) (p = 0.049) in SCRT than Conv RT arm. Anxiety scores between two arms was not significant at 5 years but mean depression scores at 5 years in age group <16 years was found significantly higher in Conv RT arm (p = 0.01). Patients in Conv RT also had significantly more neurocognitive decline in LOTCA battery at 5 years (p = 0.019), particularly in visuomotor organization and attention-concentration domains. CONCLUSIONS: We demonstrate high-precision conformal radiotherapy superior to conventional radiotherapy in preservation of neuropsychological functions in young patients with benign/low grade brain tumors. This is among few trials generating evidence for use of modern conformal RT from an appropriately-powered trial with clinically relevant endpoints and act as suitable benchmark for testing newer RT- technologies.