Clinical outcomes in a large pediatric cohort of patients with ependymoma treated with proton radiotherapy

Radiotherapy dosing in intracranial ependymoma using the national cancer database

PURPOSE

To determine the dose-dependent effect of adjuvant radiotherapy on survival for pediatric intracranial ependymomas and explore patient and disease characteristics that experience survival benefit from higher doses.

METHODS

Data was accessed from the National Cancer Database. Inclusion criteria was comprised of a diagnosis of non-metastatic intracranial ependymoma, World Health Organization (WHO) grade 2 or 3, surgical resection, adjuvant radiotherapy between 4500-6300 cGy, and non-missing survivorship data. Crude and adjusted Cox proportional hazard ratios (HRs) were calculated to estimate the associations of patient, tumor, and treatment characteristics with overall survival (OS). Kaplan-Meier (KM) estimations were used to visualize survival curves for dosing for the general cohort and by subgroups (age, resection extent, and grade).

RESULTS

Of the 1154 patients who met inclusion criteria, 405 received ≤ 5400 cGy and 749 received > 5400 cGy. We found no difference in OS crude (0.95, 95% CI 0.72-1.06) or adjusted (0.88, 95% CI 0.46-1.69) HR for those receiving ≤ 5400 cGy. KM curves showed no difference in OS for dosing for the general cohort based on age, surgical extent, and grade. However, there was better OS in those with WHO grade 2 tumors compared to grade 3 regardless of dose received.

CONCLUSIONS

There was no difference in OS between patients who received ≤ 5400 cGy compared to > 5400 cGy. We found improved OS in those with grade 2 tumors compared to grade 3, however there was no difference in OS based on dose received by tumor grade, age, or resection extent. Limitations in data available prevent exploring other outcomes or toxicity.

Systematic Review and Meta-Analysis of Adjuvant Radiation Dose for Pediatric Patients (≤22 years) with Nonmetastatic Intracranial Ependymomas

PURPOSE

Ependymomas are the third most common brain tumors in children. Standard of care is surgery followed by adjuvant radiation therapy. Controversy in the literature still exists over optimal radiation therapy dose. We completed a systematic review and meta-analysis to determine the optimal dose for local control (LC), event-free survival (EFS), and overall survival (OS) in pediatric patients.

METHODS AND MATERIALS

We searched MEDLINE (PubMed), Cochrane Database of Systematic Reviews, and Web of Science through January 2024. We included cohort studies that compared adjuvant radiation therapy of ≤54 Gy with >54 Gy in pediatric patients (≤22 years) with nonmetastatic intracranial ependymomas. We assessed study quality using the Newcastle-Ottawa Quality Assessment Scale of Cohort Studies. We pooled studies using a random effects meta-analysis for hazard ratios (HR), 95% confidence intervals (CI), and assessed statistical heterogeneity via I2. When HRs were unavailable, we transformed risks using established methods. We narratively summarized qualitative outcomes.

RESULTS

Seven studies met our inclusion criteria, covering a combined 1321 patients. Studies included a range of doses from 45 to 66.6 Gy. Compared with >54 Gy, we found no difference in LC for those receiving ≤54 Gy (HR, 0.83; 95% CI, 0.56-1.24; I2, 49.1%), in EFS (HR, 1.02; 95% CI, 0.95-1.09; I2, 0.00%), and OS (HR, 0.99; 95% CI, 0.82-1.20; I2, 37.5%). Two studies reported on subtotal resection by radiation therapy dose, neither study reporting statistical differences in LC, EFS, or OS, although the number of patients was small (n ≤ 30). Five studies reported on late effects, with brainstem radionecrosis, radiation-induced vasculopathy, and secondary tumors being the most frequent. Overall study quality was high, although lower scores were consistently seen in comparability of cohorts. To our knowledge, no studies reported on molecular subgroups.

CONCLUSIONS

We found no difference in LC, EFS, or OS for those treated with ≤54 Gy compared with >54 Gy. There were insufficient data to complete a subgroup meta-analysis on radiation therapy dosing based on extent of resection or molecular subgroups.

Brainstem toxicity after proton or photon therapy in children and young adults with localized intracranial ependymoma: A French retrospective study

BACKGROUND AND PURPOSE

Ependymoma is the third most frequent childhood braintumor. Standard treatment is surgery followed by radiation therapy including proton therapy (PBT). Retrospective studies have reported higher rates of brainstem injury after PBT than after photon therapy (XRT). We report a national multicenter study of the incidence of brainstem injury after XRT versus PBT, and their correlations with dosimetric data.

MATERIAL AND METHODS

We included all patients aged < 25 years who were treated with PBT or XRT for intracranial ependymoma at five French pediatric oncology reference centers between 2007 and 2020. We reviewed pre-irradiation MRI, follow-up MRIs over the 12 months post-treatment and clinical data.

RESULTS

Of the 83 patients, 42 were treated with PBT, 37 with XRT, and 4 with both (median dose: 59.4 Gy, range: 53‑60). No new or progressive symptomatic brainstem injury was found. Four patients presented asymptomatic radiographic changes (punctiform brainstem enhancement and FLAIR hypersignal), with median onset at 3.5 months (range: 3.0‑9.4) after radiation therapy, and median offset at 7.6 months (range: 3.7‑7.9). Two had been treated with PBT, one with XRT, and one with mixed XRT-PBT. Prescribed doses were 59.4, 55.8, 59.4 and 54 Gy.

CONCLUSION

Asymptomatic radiographic changes occurred in 4.8% of patients with ependymoma in a large national series. There was no correlation with dose or technique. No symptomatic brainstem injury was identified.

Proton Beam Therapy for Pediatric Tumors of the Central Nervous System-Experiences of Clinical Outcome and Feasibility from the KiProReg Study

As radiotherapy is an important part of the treatment in a variety of pediatric tumors of the central nervous system (CNS), proton beam therapy (PBT) plays an evolving role due to its potential benefits attributable to the unique dose distribution, with the possibility to deliver high doses to the target volume while sparing surrounding tissue. Children receiving PBT for an intracranial tumor between August 2013 and October 2017 were enrolled in the prospective registry study KiProReg. Patient's clinical data including treatment, outcome, and follow-up were analyzed using descriptive statistics, Kaplan-Meier, and Cox regression analysis. Adverse events were scored according to the Common Terminology Criteria for Adverse Events (CTCAE) 4.0 before, during, and after PBT. Written reports of follow-up imaging were screened for newly emerged evidence of imaging changes, according to a list of predefined keywords for the first 14 months after PBT. Two hundred and ninety-four patients were enrolled in this study. The 3-year overall survival of the whole cohort was 82.7%, 3-year progression-free survival was 67.3%, and 3-year local control was 79.5%. Seventeen patients developed grade 3 adverse events of the CNS during long-term follow-up (new adverse event n = 7; deterioration n = 10). Two patients developed vision loss (CTCAE 4°). This analysis demonstrates good general outcomes after PBT.

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

Background

Radiotherapy (RT) of ependymoma in children is an important part of the interdisciplinary treatment concept. However, feasibility and dose concepts are still under investigation, particularly in very young children. The aim of this study was to evaluate the standard dose and volume of proton therapy (PT) in children with ependymoma.

Methods

In this analysis, 105 patients with localized, intracranial ependymoma under the age of 18 years treated with PT between 2013 and 2018 were included. Patient characteristics, treatment, outcome, and follow-up data were analyzed using descriptive statistics, Kaplan-Meier, and Cox regression analysis.

Results

The median age of patients at PT was 2.8 years (0.9-17.0 years). The molecular subgroup analysis was performed in a subset of 50 patients (37 EP-PFA, 2 EP-PFB, 7 EP-RELA, 2 EP-YAP, 2 NEC [not elsewhere classified]). The median total dose was 59.4 Gy (54.0-62.0 Gy). The median follow-up time was 1.9 years. The estimated 3-year overall survival (OS), local control (LC), and progression-free survival (PFS) rates were 93.7%, 74.1%, and 55.6%, respectively. Within univariable analysis, female gender and lower dose had a positive impact on OS, whereas age ≥4 years had a negative impact on OS and PT given after progression had a negative impact on PFS. In the multivariable analysis, multiple tumor surgeries were associated with lower PFS. New ≥3° late toxicities occurred in 11 patients.

Conclusion

For children with localized ependymoma, PT was effective and well tolerable. Multiple surgeries showed a negative impact on PFS.

Polish Multi-Institutional Study of Children with Ependymoma-Clinical Practice Outcomes in the Light of Prospective Trials

We performed a multi-institutional analysis of 74 children with ependymoma to evaluate to what extent the clinical outcome of prospective trials could be reproduced in routine practice. The evaluation of factors that correlated with outcome was performed with a log rank test and a Cox proportional-hazard model. Survival was estimated with the Kaplan–Meier method. The majority of patients had brain tumours (89%). All had surgery as primary treatment, with adjuvant radiotherapy (RTH) and chemotherapy (CTH) applied in 78% and 57%, respectively. Median follow-up was 80 months and 18 patients died. Five- and 10-year overall survival (OS) was 83% and 73%. Progression was observed in 32 patients, with local recurrence in 28 cases. The presence of metastases was a negative prognostic factor for OS. Five- and 10-year progression-free survival (PFS) was 55% and 40%, respectively. The best outcome in patients with non-disseminated brain tumours was observed when surgery was followed by RTH (+/−CTH afterwards; p = 0.0001). Children under 3 years old who received RTH in primary therapy had better PFS (p = 0.010). The best outcome of children with ependymoma is observed in patients who received radical surgery followed by RTH, and irradiation should not be omitted in younger patients. The role of CTH remains debatable.

Effect of Postoperative Radiation Therapy Timing on Survival in Pediatric and Young Adult Ependymoma

Purpose

Postoperative radiation therapy (RT) is commonly used for World Health Organization grade II-III intracranial ependymoma. Clinicians generally aim to begin RT ≤5 weeks after surgery, but postoperative recovery and need for second look surgery can delay the initiation of adjuvant therapy. On ACNS 0831, patients were required to enroll ≤8 weeks after initial surgery and begin adjuvant therapy within 3 weeks after enrollment. The purpose of this study was to determine the optimal timing of RT after surgery.

Methods and Materials

The National Cancer Database was queried for patients (aged 1-39 years) with localized World Health Organization grade II-III intracranial ependymoma treated with surgery and postoperative RT. Overall survival (OS) curves were plotted based on RT timing (≤5 weeks, 5-8 weeks, and >8 weeks after surgery) and were compared by log-rank test. Factors associated with OS were identified by multivariate analysis. After 2009, complete data were available on whether patients underwent gross total resection or subtotal resection. Planned subset analysis was performed to examine the effect of RT timing on OS in patients with known extent of resection.

Results

In the final analytical data set of 1043 patients, no difference in 3-year OS was observed in patients who initiated RT ≤5 weeks, 5 to 8 weeks, and >8 weeks after surgery (89.8% vs 89.1% vs 88.4%; P = .796). On multivariate analysis, grade III tumors (hazard ratio, 2.752; 95% confidence interval, 1.969-3.846, P < .001) and subtotal resection (hazard ratio, 2.253; 95% confidence interval, 1.405-3.611, P < .001) were significantly associated with reduced OS. Timing of RT, total RT dose, age, and other factors were not significant. These findings were affirmed in the subset of patients treated between 2010 and 2016, when extent of resection was routinely recorded.

Conclusions

Delayed postoperative RT was not associated with inferior survival in patients with intracranial ependymoma. Delayed RT initiation may be acceptable in patients who require longer postoperative recovery or referral to an appropriate RT center, but should be minimized whenever practical.