Background: Indications for external beam radiation therapy (EBRT) for atypical meningiomas (AM) remain unclear.
Objective: To analyze features associated with recurrence in AM patients following gross total resection (GTR) and assess relative benefit of EBRT in a retrospective cohort study.
Methods: 151 primary AMs after GTR (88 female, median follow-up - 45.0 months) were examined for possible predictors of recurrence (age, gender, location, volume, bone involvement, brain invasion). Fisher's Exact Test and Wilcoxon Rank Sum tests were used to analyze association between these predictors and use of EBRT. Impact on recurrence for these predictors and EBRT was analyzed using Kaplan-Meier and Cox Regression.
Results: 13/151 patients (8.6%) experienced recurrence after GTR (median 47.0 months). Multivariate analysis identified elevated mitotic index (p = 0.007) and brain invasion (p = 0.002) as predictors of recurrence. Larger volume (p = 0.96) was not associated with recurrence but was more likely to prompt EBRT (p = 0.001). Recurrences occurred in 11/112 with GTR (9.8%, median 44 months), and 2/39 with GTR/EBRT (5.1%, median 133 months). The 2-, 5-, and 10-year progression-free survival (PFS) after GTR vs. GTR/EBRT was 97%, 86%,and 68% and 100%, 100 %, and 78%. Kaplan-Meier analysis demonstrated no difference in PFS or overall survival (OS) after GTR vs. GTR/ EBRT (p = 0.8, p = 1.0).
Conclusion: Brain invasion and high mitotic rates may predict recurrence. After GTR of AMs, EBRT appears not to impact PFS and OS, suggesting that observation rather than EBRT may be indicated after GTR.
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