Extent of Resection and Survival Outcomes in World Health Organization Grade II and III Meningiomas

Background: Meningiomas account for 13 to 26% of all intracranial tumors, and while most are benign, a substantial portion of them can be more aggressive. These high-grade meningiomas can be classified as World Health Organization (WHO) grade II or III. While complete resection in low-grade meningiomas is associated with a relatively low recurrence rate, high-grade meningiomas are more aggressive, with recurrence rates reported between 29 and 94%. The purpose of this study is to describe the association of extent of resection with progression-free and overall survival in patients with WHO grade II and III meningiomas ([Fig. 1]).

Methods: A retrospective database review was performed to identify all patients who underwent surgical resection for WHO grade II and III meningiomas at our institution between 1995 and 2019. Patients undergoing surgery for recurrent tumors, or for whom adequate demographic or surgical information was unavailable, were excluded from the study. Patients were divided into two cohorts based on the extent of surgical resection. Patients undergoing Simpson’s grade I or II resection were classified as gross total resection (GTR), and patients undergoing Simpson’s grade III or IV resection were classified as subtotal resection (STR). Two-sided unpaired t-tests and Fisher’s exact tests were used as appropriate to compare demographic and tumor-specific factors between the cohorts. Kaplan–Meier curves and log-rank analyses were used to plot and assess overall and progression-free survival. A p-value of <0.05 was considered to be statistically significant ([Fig. 2]).

Results: A total of 216 patients who underwent surgical resection for WHO grade II or III meningiomas were included in this study. Median follow-up in this study was 45.0 months. Of these patients, 159 had gross total resection and 57 had subtotal resection. There were no significant differences between the two cohorts with respect to age, gender, race, preoperative Karnofsky’s performance status (KPS), proportion of WHO grade II/III tumors, or patients receiving chemotherapy. Radiation was significantly more common in the STR cohort than in the GTR cohort (p = 0.012). Additionally, tumors within the STR cohort were more likely to be located in the sphenoid wing and other skull base locations and less likely to be convexity tumors (p = 0.008). Kaplan–Meier curves showed a significant difference in overall survival between GTR and STR cohorts (p = 0.042), but there was no statistically significant difference in progression-free survival between the cohorts (p = 0.71).

Conclusion: Despite an increased proportion of patients within the STR cohort undergoing radiation therapy postoperatively, greater extent of resection significantly correlated with prolonged overall survival. In an era of increasing support for adjuvant treatment modalities in the management of meningiomas, our data reinforce the belief that the goal of surgery for these tumors should remain maximal safe resection.