Neuro-OncologyPhase 3 Randomized Trial of Postirradiation Chemotherapy in Patients with Newly Diagnosed Ependymoma: A Report from the Children’s Oncology Group

ℹ️ Observational Association Only Evidence

COG ACNS0831, the largest randomized trial in pediatric intracranial ependymoma, evaluated whether maintenance chemotherapy following focal radiation improved survival in patients aged 1–21 years. The study also provided prospective molecular classification for 94% of 449 enrolled patients using updated WHO criteria.

Clinical Considerations

• Maintenance chemotherapy after RT showed no significant improvement in 5-year EFS or OS in completely resected ependymoma (EFS: 69.2% vs 63.7%, p=0.299); both as-randomized and as-treated analyses were consistent
• Supratentorial grade 2 tumors with complete resection achieved 100% OS under observation alone; surgery without adjuvant therapy is supported for this subgroup
• PFA tumors with 1q gain showed 5-year EFS of 34% vs 71% without gain (p<0.001); 6q loss was even more severe at 19% 5-year EFS vs 64%. Both confirmed prospectively for the first time.
• Subtotal resection carries substantially worse prognosis regardless of chemotherapy: 5-year EFS 33.6%, OS 74.0%

Practice Applications

• Recognize extent of resection as the dominant modifiable prognostic factor — maximal safe resection remains the treatment priority
• Integrate molecular classification (PFA/PFB, ZFTA/YAP1; 1q/6q status) into prognostic counseling for families of children with posterior fossa ependymoma
• Avoid framing maintenance chemotherapy as standard adjuvant care following complete resection and radiation as current evidence does not support it
• Monitor for late relapse – 10-year EFS data remain pending; OS conclusions on chemotherapy benefit are premature