Adjuvant Radiation Does Not Decrease the Risk of Short-Term Tumor Recurrence in Patients with Atypical Meningioma

Purpose: Intracranial atypical meningiomas (WHO grade II) represent a significant challenge for the treating surgeon. While not histologically benign, the ability to risk-stratify patients into high and low risk for recurrence, and thus who may benefit from adjuvant therapies, remains elusive.

Methods: A single institution, retrospective analysis of prospectively acquired patients between 2000 and 2018 was performed. Clinical data and radiographic parameters were reviewed to calculate progression-free survival and overall survival in patients undergoing microsurgical resection and those undergoing microsurgical resection with adjuvant radiation.

Results: Between 2000 and 2018 a total of 143 patients met the inclusion criteria for this study. A total of 85 patients underwent microsurgical resection only and 58 underwent microsurgical resection with adjuvant radiation. A greater percentage of patients achieved gross total resection in the microsurgery only group (p < 0.001); however, there was no difference in progression-free survival or overall survival as compared with those patients who received adjuvant radiation. There was an improvement in progression-free survival in those patients undergoing microsurgical resection (p = 0.047) and a trend toward improved progression-free survival in the microsurgery and adjuvant radiation cohorts (p = 0.18) in tumors in skull base as compared with nonskull base locations, though adjuvant radiation did not improve the outcomes of either subset of patients compared with microsurgery alone. Of those patients who failed initial treatment, a majority were in nonskull base locations, were associated with a more aggressive histological phenotype, were male, and were more likely to succumb to disease during the study period.

Conclusion: Adjuvant radiation does not improve short-term progression-free survival in patients who undergo gross total resection of atypical meningiomas over a follow-up of approximately 4 years. In addition to extent of resection, sex, histological characteristics, and tumor location should be included in the algorithm for determining the utility of adjuvant radiotherapy.