Atypical meningioma: Randomized trials are required to resolve contradictory retrospective results regarding the role of adjuvant radiotherapy
Hannah Yoon1, Minesh P Mehta2, Karthikeyan Perumal3, Irene B Helenowski4, Richard J Chappell5, Erinc Akture3, Yunzhi Lin5, Mary Anne H Marymont6, Samir Sejpal6, Andrew Parsa7, James R Chandler7, Bernard R Bendok7, Joshua Rosenow7, Shahriar Salamat8, Priya Kumthekar8, Jeffrey K Raizer9, Mustafa K Baskaya3
1 Department of Radiation Oncology, Stony Brook Medicine, Stony Brook, New York, USA
2 Department of Radiation Oncology, University of Maryland, Baltimore, Maryland, USA
3 Department of Neurological Surgery, University of Wisconsin, Madison, Wisconsin, USA
4 Department of Preventive Medicine, Northwestern University, Chicago, Illinois, USA
5 Department of Statistics, University of Wisconsin, Madison, Wisconsin, USA
6 Department of Radiation Oncology, Northwestern University, Chicago, Illinois, USA
7 Department of Neurological Surgery, Northwestern University, Chicago, Illinois, USA
8 Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, Wisconsin, USA
9 Department of Neurology, Northwestern University, Chicago, Illinois, USA
Mustafa K Baskaya
Associate Professor, Director of Skull Base Surgery, Department of Neurological Surgery, University of Wisconsin Hospital and Clinics, CSC K4/828, 600 Highland Avenue, Madison, Wisconsin - 53792
Source of Support: None, Conflict of Interest: None
Background: The role of postoperative radiation (RT) in atypical meningioma remains controversial.
Materials and Methods: We report a retrospective review of outcomes and prognostic factor analysis in 158 patients treated between 2000 and 2010, and extensively review the literature.
Results: Following resection, 23 patients received immediate RT, whereas 135 did not. Median progression-free survival (PFS) with and without RT was 59 (range 43-86) and 88 (range 64-123) months. For Simpson grade (G) 1-3 resection, with and without RT, median PFS was 48 (2-80) versus 96 (88-123) months and for Simpson G4, it was 59 (6-86) versus 47 (15-104) months (P = 0.4). The rate of 5-year overall survival (OS) with and without RT was 89% and 83%, respectively. On univariate analysis, Simpson G4 (HR 3.2, P = 0.0006) and brain invasion (HR 2.2, P = 0.03) were significantly associated with progression, whereas age >60 years (HR 9.7, P = 0.002), mitoses >5 per 10 high-power field (0.2, P = 0.0056), and Simpson G4 (HR 2.4, P = 0.07) were associated with higher risk of death. We summarized 22 additional reports, which provide very divergent results regarding the benefit of RT.
Conclusions: In our series, adjuvant RT is surprisingly associated with worse PFS and OS, and this is more likely to be due to selection bias of referring tumors with more aggressive characteristics such as elevated Ki-67 and brain invasion for adjuvant RT, rather than a direct causal effect of adjuvant RT. Although there is a trend toward improved PFS with adjuvant RT after subtotal resection, no improvement was noted in OS. Multivariate analysis did not yield statistical significance for any of the factors including Simpson grades of resection, adjuvant RT, or six pathological defining features. The relatively divergent results in the literature are most likely explained by patient selection variability; therefore, randomized trials to adequately address this question are clearly necessary.