Feasibility of Dose Escalation in Patients With Intracranial Pediatric Ependymoma

Abstract

Background and purpose: Pediatric ependymoma carries a dismal prognosis, mainly owing to local relapse within RT fields. The current prospective European approach is to increase the radiation dose with a sequential hypofractionated stereotactic boost. In this study, we assessed the possibility of using a simultaneous integrated boost (SIB), comparing VMAT vs. IMPT dose delivery. Material and methods: The cohort included 101 patients. The dose to planning target volume (PTV59.4) was 59.4/1.8 Gy, and the dose to SIB volume (PTV67.6) was 67.6/2.05 Gy. Gross tumor volume (GTV) was defined as the tumor bed plus residual tumor, clinical target volume (CTV59.4) was GTV + 5 mm, and PTV59.4 was CTV59.4 + 3 mm. PTV67.6 was GTV+ 3 mm. After treatment plan optimization, quality indices and doses to target volume and organs at risk (OARs) were extracted and compared with the standard radiation doses that were actually delivered (median = 59.4 Gy [50.4 59.4]). Results: In most cases, the proton treatment resulted in higher quality indices ( p < 0.001). Compared with the doses that were initially delivered, mean, and maximum doses to some OARs were no higher with SIB VMAT, and significantly lower with protons ( p < 0.001). In the case of posterior fossa tumor, there was a lower dose to the brainstem with protons, in terms of V59 Gy, mean, and near-maximum (D2%) doses. Conclusion: Dose escalation with intensity-modulated proton or photon SIB is feasible in some patients. This approach could be considered for children with unresectable residue or post-operative FLAIR abnormalities, particularly if they have supratentorial tumors. It should not be considered for infratentorial tumors encasing the brainstem or extending to the medulla.

Evaluation of dose, volume, and outcome in children with localized, intracranial ependymoma treated with proton therapy within the prospective KiProReg Study

“…However, concerns about feasibility remain, particularly regarding very young children, after multiple surgeries or patients with neurological impairments. 10 , 15 Therefore, it is an open question for whom doses can be limited to 54 Gy in order to best balance treatment intensity in this vulnerable group of patients. 27 , 38 According to our findings, no significant difference regarding LC and PFS between patients receiving radiation doses lower or higher than 59 Gy was observed within univariate analysis.…”

Postoperative Recurrent Ependymoma Prognosis in Adolescents: A Meta-Analysis

“…Grade III corresponds to anaplastic ependymoma, which is a malignant tumor characterized by a high nuclear-to-cytoplasmic ratio and a high mitotic count. However, due to the heterogeneity of the tumors, distinguishing between Grades II and III solely based on histopathology can be challenging [3,4]. In recent years, advances in immunohistochemistry, transcriptome analysis, and methylation profiling have redefined the biological properties of ependymoma.…”

“…As a relatively rare malignant tumor of the central nervous system, ependymoma (EPN) can occur at any age and can involve various locations along the neural axis. Ependymoma accounts for approximately 7% of all neuroglial tumors, with a higher incidence in males than in females [3,6]. Ependymal tumors have the potential to spread within the nervous system, including the spinal cord, through cerebrospinal fluid dissemination.…”