Background
Prospective neurocognitive substudy of ACNS0121 (COG phase II ependymoma trial). 84 children with intracranial ependymoma treated with conformal RT 59.4 Gy. Evaluated longitudinal neurocognitive outcomes including IQ, memory, attention, and academic achievement through serial neuropsychological testing.
Interventions and follow up
Arm A: Conformal RT 59.4 Gy (1.8 Gy/fx) — neurocognitive testing at baseline, 6, 12, 24, 36 months post-RT
Primary endpoint: Change in full-scale IQ (FSIQ) over time post-RT
mFollow up: 3 year
Primary endpoint: Change in full-scale IQ (FSIQ) over time post-RT
mFollow up: 3 year
Results
FSIQ decline: Mean −1.5 points/year (statistically significant)
Working memory decline: Significant, especially in younger children (<3 years at RT)
Processing speed: Significant decline over time
Academic achievement: Reading, math, spelling declined over time
Working memory decline: Significant, especially in younger children (<3 years at RT)
Processing speed: Significant decline over time
Academic achievement: Reading, math, spelling declined over time
Adverse events
Main adverse events: Neurocognitive: IQ decline most pronounced in children <3 years at treatment and those with supratentorial tumors. Attention deficits and learning disabilities common. No grade ≥3 neurologic toxicities reported separately in this analysis.
Conclusions
Conformal RT for pediatric ependymoma is associated with progressive neurocognitive decline, particularly in younger children. The magnitude of IQ decline (~1.5 points/year) emphasizes the need for strategies to reduce neurocognitive toxicity including proton therapy and neurocognitive rehabilitation.
Key Limitations
Key Limitations: Single-arm; no comparison group. Attrition in serial testing. Pre-existing neurocognitive deficits related to tumor and surgery not fully separated from RT effects. Age at treatment and tumor location as confounders are difficult to isolate.
Clinical Context
These data support the use of proton therapy for pediatric ependymoma to reduce integral brain dose and potentially mitigate neurocognitive late effects. Neurocognitive monitoring and early intervention (tutoring, neuropsychological support) are now standard of care after cranial RT in children.
References
References: Merchant TE et al, JCO 2015 (ACNS0121 primary)