Radiopathologic predictors of recurrence in patients with a gross totally resected atypical meningioma

Background Atypical meningiomas (AM) comprise a heterogeneous conglomeration of meningiomas with higher local recurrence rates than their benign counterparts. Although adjuvant therapy following subtotal resection is the standard, the use of adjuvant therapy following gross total resection (GTR) remains controversial. This study seeks to add to the literature by identifying radiopathologic predictors of recurrence in patients with a GTR AM and better identify those patients who may benefit from adjuvant therapy. Methods A total of 103 consecutive patients who received gross total resection for AM at our center between Apr 2010 and Apr 2019 were evaluated retrospectively. Recurrence was defined as new enhancing masses on MRI without requiring biopsy confirmation. Cumulative incidence plots were used to estimate survival, and the log-rank test was used to assess differences between groups. Cox proportional hazards models were used to evaluate the effect of radiopathologic variables on the hazard of recurrence. Results Of the 103 patients included in this study, 68 (66.0%) were female, and the mean age was 51.1 +/- 11.4. The median overall survival for patients following surgery was 71 months while the median progression-free survival was 64 months. Recurrence occurred in 36 (35.0%) patients. Factors correlated with AM recurrence following GTR included peritumoral edema (p = 0.005), necrosis (p < 0.001), mitotic rate greater than 7/10 high-power field (HPF) (p < 0.001), and Ki67 > 15% (p < 0.001). However, following Cox proportional hazards regression analysis, only mitotic rate greater than 7/10HPF (p = 0.018) and Ki67 > 15% (p = 0.035) were significantly associated with AM recurrence. Conclusions Our results showed high mitotic index (greater than 7/10 HPF) and Ki67 greater than 15% as independent predictors of recurrence in patients with a GTR AM. These findings could help stratify patients who may benefit from adjuvant therapy.