Analyzing the role of adjuvant or salvage radiotherapy for spinal myxopapillary ependymomas

Abstract

OBJECTIVE The authors sought to describe the long-term recurrence patterns, prognostic factors, and effect of adjuvant or salvage radiotherapy (RT) on treatment outcomes for patients with spinal myxopapillary ependymoma (MPE). METHODS The authors reviewed a tertiary institution IRB-approved database and collected data regarding patient, tumor, and treatment characteristics for all patients treated consecutively from 1974 to 2015 for histologically confirmed spinal MPE. Key outcomes included relapse-free survival (RFS), postrecurrence RFS, failure patterns, and influence of timing of RT on recurrence patterns. Cox proportional hazards regression and Kaplan-Meier analyses were utilized. RESULTS Of the 59 patients included in the study, the median age at initial surgery was 34 years (range 12–74 years), 30 patients (51%) were female, and the most common presenting symptom was pain (n = 52, 88%). Extent of resection at diagnosis was gross-total resection (GTR) in 39 patients (66%), subtotal resection (STR) in 15 (25%), and unknown in 5 patients (9%). After surgery, 10 patients (17%) underwent adjuvant RT (5/39 GTR [13%] and 5/15 STR [33%] patients). Median follow-up was 6.2 years (range 0.1–35.3 years). Overall, 20 patients (34%) experienced recurrence (local, n = 15; distant, n = 5). The median RFS was 11.2 years (95% CI 77 to not reached), and the 5- and 10-year RFS rates were 72.3% (95% CI 59.4–86.3) and 54.0% (95% CI, 36.4–71.6), respectively. STR was associated with a higher risk of recurrence (HR 6.45, 95% CI 2.15–19.23, p < 0.001) than GTR, and the median RFS after GTR was 17.2 years versus 5.5 years after STR. Adjuvant RT was not associated with improved RFS, regardless of whether it was delivered after GTR or STR. Of the 20 patients with recurrence, 12 (60%) underwent salvage treatment with surgery alone (GTR, n = 6), 4 (20%) with RT alone, and 4 (20%) with surgery and RT. Compared to salvage surgery alone, salvage RT, with or without surgery, was associated with a significantly longer postrecurrence RFS (median 9.5 years vs 1.6 years; log-rank, p = 0.006). CONCLUSIONS At initial diagnosis of spinal MPE, GTR is key to long-term RFS, with no benefit to immediate adjuvant RT observed in this series. RT at the time of recurrence, however, is associated with a significantly longer time to second disease recurrence. Surveillance imaging of the entire neuraxis remains crucial, as distant failure is not uncommon in this patient population.