The Role of Adjuvant Radiotherapy in Atypical Meningioma

Abstract

Purpose: The object of this study was to analyze treatment outcomes and to identify the prognostic factors, with a focus on the role of adjuvant radiotherapy (ART), predicting disease progression in atypical meningiomas

Patients and Methods: From May 1997 and December 2011, 88 patients with meningioma were included in this study. All patients were histologically confirmed to have atypical meningioma and were treated with surgical resection with or without postoperative ART at our institution. Among them, 4 patients were diagnosed as benign meningioma (WHO grade I) initially, but the tumors recurred as atypical meningioma (WHO grade II). As primary therapy, 30 patients received surgical intervention followed by ART, and 58 patients received no adjuvant therapy. Of 88 evaluable patients, 56, 29, and 3 patients underwent complete resection, incomplete resection, and resection of unknown extent, respectively. The median ART dose was 61.2 Gy (range, 40-61.2 Gy). The median age at diagnosis was 51 years (range, 16-78 years), and the male to female ratio was 35:53.

Results: The 5- and 10-year actuarial overall survival (OS) rates were 88.7% and 59.5% and the 5- and 10-year progression-free survival (PFS) rates were both 46.2%, with a median follow-up of 42.8 months (range, 2.7–160.0 months). The median time to progression was 24.7 months (range, 0.8-157.2 months). Addition of ART (p = 0.011) and complete tumor resection (p = 0.001) were associated with superior PFS. Age at diagnosis was the only prognostic factor affecting OS (p = 0.028) on multivariate analysis. When stratified to 4 groups according to resection status and ART, the groups of patient with incomplete resection without ART showed significantly worse PFS compared to other 3 groups (p = 0.000). Of 40 patients with disease progression, 33 (82.5%) received salvage treatment. The majority of first salvage-therapy was radiosurgery using Gamma Knife irrespective of previous radiotherapy history.

Conclusions: Surgical resection followed by ART led to lower local tumor progression in patients with atypical meningioma defined by the updated 2000/2007 WHO classification. Our results may contribute to the notion in favor of the routine use of radiotherapy as an adjuvant treatment for such lesions, especially after incomplete resection, until the outcomes of ongoing prospective trials are available.