Outcomes of Single-Institution Retrospective Case Series on Observation Alone Following Atypical Meningioma Resection

Abstract

Abstract INTRODUCTION Observation alone vs adjuvant radiotherapy (RT) following gross total resection (GTR) of WHO Grade II (G2) meningiomas is controversial. Local recurrence (LR) rates have been reported to be similar. We present LR rates in patients who were observed following G2 meningioma resection and correlate with Simpson grades. METHODS Patients from 2005 to 2018 who underwent observation alone following surgical resection of G2 meningiomas at a single institution were analyzed in a retrospective case series. Simpson grades were used to classify extent of tumor resection. Patients were followed with magnetic resonance imaging (MRI) or computed tomography (CT) imaging at 1-mo, 3-mo, 6-mo, and 12-mo postoperatively, then annually thereafter to monitor for recurrence. Descriptive 2-yr, and 5-yr LR rates for our entire cohort and time to recurrence by Simpson grade are reported. RESULTS A total of 28 patients with Simpson 1 to 4 resections for G2 meningiomas did not undergo adjuvant RT and were included. Median follow-up (FU) was 34 mo [Interquartile range (IQR): 18-55 mo]. Median time to LR was 55 mo (IQR: 44-65 mo) across our entire cohort. Of 14 patients with Simpson 1 resection, there was 1 LR at 68 mo. Of 3 patients with Simpson 2 resection, there was 1 LR at 49 mo. Of 9 patients with Simpson 3 resection, there were 5 recurrences; median time to LR was 61 mo. Of 2 patients with Simpson 4 resections, there was 1 LR at 3 mo. Overall, 2-yr LR was 3.6% and 5-yr LR was 10.7%. There was no statistically significant difference in LR rate between Simpson 1 vs Simpson 2 to 4 resections (P = .11). CONCLUSION Our results are consistent with the low recurrence rate of G2 meningiomas undergoing observation along following GTR in current literature. Simpson grade 1 resections have low overall LR rate and larger scale studies are needed to determine if statistical significance exists.