Long-Term Outcomes of Newly Diagnosed Resected Atypical Meningiomas and the Role of Adjuvant Radiotherapy.

Objective: The role of adjuvant radiotherapy (ART) in patients with World Health Organization Grade II atypical meningiomas (AMs) remains controversial.

Methods: We retrospectively reviewed 149 patients with newly diagnosed resected AMs from 2000 to 2012. Gross total resection (GTR) was defined as Simpson Grades I-III and subtotal resection (STR) as Grades IV and V. Kaplan-Meier analyses of local control (LC), progression-free survival (PFS), and overall survival were performed with the log-rank test, and risk factors for progression/recurrence (P/R) were analyzed with multivariate Cox regression.

Results: Median follow-up was 74.2 months. GTR was achieved in 98 patients and STR in 51 patients. Fifty-three (35%) patients received ART. Overall, 46 patients (31%) experienced P/R with a median time to P/R of 32.4 months. ART was associated with a trend toward improved PFS (P = 0.0669) in the GTR subset but significantly improved LC (P = 0.0183) and PFS (P = 0.0034) in the STR subset. Age, tumor size, and STR were significant risk factors for worse PFS, whereas receiving ART was associated with improved PFS on multivariate analyses. Thirty-nine of the 46 progressive/recurrent patients underwent salvage therapy with only 22 patients experiencing long-term control. Five patients experienced transformation to World Health Organization Grade III malignant meningioma.

Conclusions: Patients who undergo STR for newly diagnosed AM should receive ART based on improvements in LC and PFS. GTR patients should be considered for ART, but active surveillance is a reasonable management approach with the recognition that progressive/recurrent disease can act aggressively. Prospective, randomized trials are currently underway to evaluate the role of ART.