NCOG-10. High-Precision Radiotherapy Improves Long-term tumor control and Survival, Preserves Neurocognitive and Endocrine Function in Paediatric Low-Grade Gliomas: A Subset Analysis of a Randomized Trial (NCT00517959)

BACKGROUND Pediatric low-grade gliomas (LGGs) are the most common childhood brain tumours with good long-term survival, but survivors risk late neurological sequelae. Radiotherapy (RT) is key for tumour control post-surgery.This subset analysis from a Randomized Controlled Trial compares conventional RT (ConvRT) and Stereotactic Conformal RT (SCRT) to assess clinical benefits of advanced techniques. METHODS One hundred two LGG patients (SCRT: 56; ConvRT: 46; Dose: 54 Gy in 30 fractions) were analysed to assess the clinical impact of dosimetric sparing on neurocognitive & endocrine function, overall survival (OS), and local control (LC). Neurocognitive outcomes were measured from baseline to five years post-RT using age-appropriate Wechsler Scales (WISC/WAIS). Trends were analysed by Linear Mixed-Effects (LME) model. RESULTS Median age was 12 years (IQR: 8–18). At a median follow-up of 147 months (IQR: 72.6–203.8), the 12-year LC was 91.3% (95% CI: 85.7–97.2) with no significant differences by treatment arm (p=0.2), extent of resection (EoR) (p=0.3), or histology (p=0.6). The 12-year OS was 83.8% (95% CI: 76.5–91.7). Improved OS was significantly associated with SCRT (90.5%, vs ConvRT (75.1%,HR 0.32, p=0.035), younger age (p=0.027), and greater EoR (p=0.01 for gross/near-total excision vs biopsy).SCRT significantly improved the full-scale IQ trajectory (+1.79 points/year, p=0.040), and a trend toward improved performance quotient (+2.14, p=0.052). At 5 years, freedom from cognitive decline (≥5-point IQ drop) was higher with SCRT (57.1% vs. 35.4%; HR=0.48,p=0.027). Higher age reduced the risk of cognitive decline (HR=0.90, p=0.003), with SCRT benefits limited to patients <15 years (p=0.016; p=0.9 for ≥15 years). Neuroendocrine dysfunction was significantly lower with SCRT (39.5% vs. 58.1%, p=0.03) and in tumours >2 cm from the hypothalamic-pituitary axis (26.8% vs. 71.6%, p=0.001). CONCLUSION SCRT improves long-term tumour control, survival, preserves neurocognitive and endocrine function in paediatric LGG, supporting its role as standard of care.