Proton Therapy for Pediatric Ependymoma: Mature Results from a Bicentric Study
Menée sur la période 2000-2019 auprès de 386 patients pédiatriques atteints d'un épendymome intracrânien non métastatique de grade II/III (durée médiane de suivi : 5 ans ; 56 % de garçons ; âge médian au moment du traitement : 3,8 ans), cette étude analyse l'efficacité, du point de vue du contrôle local à 7 ans, de la survie sans progression et de la survie globale, et la toxicité à long terme d'un traitement par protonthérapie
Purpose: To report the long-term efficacy and toxicity of proton therapy for pediatric ependymoma. Methods & Materials: Between 2000 and 2019, 386 children with nonmetastatic grade II/III intracranial ependymoma received proton therapy at one of two academic institutions. Median age at treatment was 3.8 years (range, 0.7-21.3); 56% were male. Most (72%) tumors were in the posterior fossa and classified as WHO grade III (65%). Eighty-five percent had a gross total or near total tumor resection before radiotherapy; 30% received chemotherapy. Median radiation dose was 55.8 GyRBE (range, 50.4-59.4). Results: Median follow-up was 5.0 years (range, 0.4-16.7). The 7-year local control, progression-free survival, and overall survival rates were 77.0% (95% CI, 71.9-81.5%), 63.8% (95% CI, 58.0-68.8%), and 82.2% (95% CI, 77.2-86.3%), respectively. Subtotal resection was associated with inferior local control (59% vs 80%; p<0.005), progression-free survival (48% vs 66%; p<0.001), and overall survival (70% vs 84%; p<0.05). Male sex was associated with inferior progression-free (60% vs 69%; p<0.05) and overall survival (76% vs 89%; p<0.05). Posterior fossa tumor site was also associated with inferior progression-free (59% vs 74%; p <0.05) and overall survival (79% vs 89%; p <0.01). Twenty-one patients (5.4%) required hearing aids; of these, 13 received cisplatin, including the 3 with bilateral hearing loss. Forty-five patients (11.7%) required hormone replacement, typically growth hormone (38/45). The cumulative incidence of grade 2+ brainstem toxicity was 4% and occurred more often in patients who received >54 GyRBE. Two patients (0.5%) died of brainstem necrosis. The second-malignancy rate was 0.8%. Conclusion: Proton therapy offers commensurate disease control to modern photon therapy without unexpected toxicity. The high rate of long-term survival justifies efforts to reduce radiation exposure in this young population. Independent of radiation modality, this large series confirms extent of resection as the most important modifiable factor for survival.
International Journal of Radiation Oncology, Biology, Physics 2021