Progression‐free survival of children with localized ependymoma treated with intensity‐modulated radiation therapy or proton‐beam radiation therapy

Abstract

BACKGROUND: The treatment for childhood intracranial ependymoma includes maximal surgical resection followed by involved-field radiotherapy, commonly in the form of intensity-modulated radiation therapy (IMRT). Proton-beam radiation therapy (PRT) is used at some centers in an effort to decrease long-term toxicity. Although protons have the theoretical advantage of a minimal exit dose to the surrounding uninvolved brain tissue, it is unknown whether they have the same efficacy as photons in preventing local recurrence. METHODS: A retrospective review of medical records from September 2000 to April 2013 was performed. Seventy-nine children with newly diagnosed localized intracranial ependymomas treated with either IMRT (n 5 38) or PRT (n 5 41) were identified, and progression-free survival (PFS) was analyzed with Kaplan-Meier and Cox multivariate analyses. RESULTS: The median age at diagnosis was 3.7 years for all patients (range, 0.4-18.7 years). There were 54 patients with infratentorial tumors (68% of the total population). Patients treated with PRT were younger (median age, 2.5 vs 5.7 years; P 5.001) and had a shorter median follow-up (2.6 vs 4.9 years; P <.0001). Gross total resection (GTR) was achieved in 67 patients (85%) and was more frequent in the PRT group versus the IMRT group (93% vs 76%; P 5.043). The 3-year PFS rates were 60% and 82% with IMRT and PRT, respectively (P 5.031). CONCLU-SIONS: Children with localized ependymomas treated with PRT have a 3-year PFS rate comparable to that of children treated with IMRT. This analysis suggests that local control is not compromised by the use of PRT. The data also support GTR as the only prognostic factor for PFS.

Clinical outcomes following proton therapy for children with central nervous system tumors referred overseas

“…Serious toxicity was limited and no unexpected side effects were observed. Specifically, the rates of symptomatic brainstem necrosis and vasculopathy in this cohort were comparable to reports of children treated with photons over the past 5 years …”

Second cancer risk after radiation therapy of ependymoma using the flattening filter free irradiation mode of a linear accelerator

“…Historically, cranial or craniospinal irradiation was the standard treatment after surgery3 in order to assure that the volume adjacent to the target receives adequate dose and consequently assure local control. However, recent publications have shown that conformal, intensity‐modulated (IMRT) and proton‐beam radiotherapy can achieve similar local control rates to those published in historical publications without an increased risk of marginal failure 4, 5, 6, 7…”

Case-based review: ependymomas in adults

“…71,72 Initial studies have shown that protons have comparable local control to photons; however, further information on comparing late toxicities has not been reported. 73 Nonetheless, recent series evaluating neurocognitive data in pediatric patients with localized ependymoma treated with photon RT have shown significantly improved outcomes with minimal impairment. 74,75 Proton RT may also be of benefit in patients receiving craniospinal RT in reducing the dose to structures in front of the spine such as the heart, lungs, bowel, breasts, and thyroid.…”