Adjuvant radiotherapy versus observation following gross total resection for atypical meningioma: a systematic review and meta-analysis

Abstract

Background: The impact of adjuvant radiotherapy (RT) on atypical meningioma (AM) underwent a gross total resection (GTR) remains unclear, showing conflicting results from various studies. The objective of this study was to perform an updated meta-analysis for observational studies to determine the effect of adjuvant RT after GTR on local recurrence and survival outcomes compared to observation after GTR.

Methods: PubMed, Embase, and Web of Science were searched to identify comparative studies that reported outcomes of adjuvant RT versus observation for AM patients after GTR. Local recurrence rate, progression-free survival (PFS), overall survival (OS), and toxicities related to RT were considered as outcomes of interest. Differences between two cohorts were estimated by calculating odds ratios (OR) for LR rate and hazard ratios (HR) for survival outcomes with 95% confidence intervals (CIs) for meta-analysis, using R version 4.0.3 software. Included studies were appraised with the Risk of Bias Assessment tool for Non-Randomized Studies. Outcome ratios were combined with the Mantel-Haenszel method and the inverse variance-weighted method, appropriately.

Results: Data from 30 studies involving 2904 patients (adjuvant RT: n = 737; observation: n = 2167) were eventually included. Significant reduction of local recurrence rate was seen in the adjuvant RT cohort compare to that in the observation cohort (OR 0.50; 95% CI 0.36-0.68; p < 0.0001). Pooled HRs of PFS at 1-year, 3-year, 5-year, and > 5-year revealed that adjuvant RT was superior to observation. There was no significant difference in OS between the two cohorts during any period. Most toxicities were tolerable with grade 1 or 2. There was no documented grade 5 toxicity.

Conclusions: For AM patients who underwent GTR, evidence suggested that adjuvant RT could potentially decrease local recurrence and improve PFS better than observation.

Keywords: Adjuvant; Atypical meningioma; Gross total resection; Postoperative; Radiotherapy.

Fig. 1

Flow diagram showing the selection of relevant studies

Fig. 2

a Forest plot comparing the risk of local recurrence between the adjuvant RT cohort and the observation cohort. The risk of local recurrence is higher in the observation cohort. b Cumulative forest plot showing pooled OR of local recurrence according to the publication year. The first row shows the effect based on one study. The second row shows the cumulative effect based on two studies, and so on

Fig. 3

Forest plots comparing the risk of local recurrence between the adjuvant RT cohort and the observation cohort in subgroups using a 1993 or 2000 WHO criteria and b 2007 or 2016 WHO criteria for included studies. The benefit of adjuvant RT in local recurrence is significantly higher in a subgroup using the 2007 or 2016 WHO criteria

Fig. 4

Forest plots showing PFS at each period of 1-year, 3-year, 5-year, and > 5-year between the adjuvant RT cohort and the observation cohort. The advantage of PFS is observed in the adjuvant RT cohort, showing increasing significance with longer period

Fig. 5

Forest plots showing OS at each period of 1-year, 3-year, 5-year, and > 5-year between the adjuvant RT cohort and the observation cohort. There was no significant difference in pooled HR of OS between the two cohorts