Impact of postoperative radiotherapy timing on survival in pediatric and young adult ependymoma

Abstract Introduction Postoperative radiotherapy is commonly used for WHO Grade II-III intracranial ependymoma. Clinicians generally aim to begin radiotherapy ≤5 weeks following 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 following initial surgery and begin adjuvant therapy within 3 weeks after enrollment. The purpose of this study is to determine the optimal timing of radiotherapy after surgery. Methods The National Cancer Database was queried for patients (ages 1-39 years) with localized WHO Grade II-III intracranial ependymoma treated with surgery and postoperative radiotherapy. Overall survival (OS) curves were plotted based on radiotherapy 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 (MVA). After 2009, complete data were available on whether patients underwent gross total resection (GTR) or subtotal resection (STR). Planned subset analysis was performed to examine the impact of RT timing on OS in patients with known extent of resection. Results In the final analytic dataset of 1,043 patients, no difference in 3-year OS was observed in patients who initiated radiotherapy ≤5 weeks, 5-8 weeks, and >8 weeks after surgery (89.8% vs. 89.1% vs. 88.4%; p=0.796). On MVA, Grade III tumors (HR 2.752, 95% CI: 1.969-3.846, p Conclusions Delayed postoperative radiotherapy was not associated with inferior survival in patients with intracranial ependymoma. Delayed radiotherapy initiation may be acceptable in patients who require longer postoperative recovery or referral to an appropriate radiotherapy center, but should be minimized whenever practical.