493 Predictors of Recurrence After Surgical Resection of Parafalcine and Parasagittal Meningiomas

INTRODUCTION: Parasagittal and parafalcine meningiomas are challenging tumors to resect, owing to their proximity to the sagittal sinus and associated collateralized venous channels. More research is needed to elucidate relevant factors that affect risk of recurrence. METHODS: This is a retrospective study of all patients who underwent resection of parasagittal and parafalcine meningiomas between 2012-2018. Multivariable Cox regression and Kaplan Meier analysis was performed to assess for factors that influence progression free survival (primary endpoint). RESULTS: A total of 110 consecutive subjects (mean age: 59.4+/-15.2 years, 67.3% female) with 74 parasagittal and 36 parafalcine meningiomas (92 WHO grade 1, 18 WHO grade 2/3) are included in the study. A total of 37 patients (33.6%) exhibited recurrence with median follow-up of 42 months (IQR: 10-71). In the overall cohort, parasagittal meningiomas exhibited shorter progression free survival compared to parafalcine meningiomas (p = 0.045). On univariate analysis, predictors of recurrence include WHO grade 2/3 vs. grade 1 tumors (HR 4.27, 95%CI: 2.01-9.09; p < 0.001), higher Ki-67 indices (HR, 1.11, 95% CI: 1.07-1.14; p < 0.001), partial (Sindou class 2-4) (HR 2.32, 95% CI: 1.03-5.19; p = 0.04) or complete (Sindou class 5-6) sinus invasion (HR 4.65, 95% CI: 2.07-10.42; p < 0.001), and subtotal resection (HR 4.13, 95% CI: 2.05-8.32; p < 0.001). Location along the anterior, middle or posterior third of the sagittal sinus did not influence risk of recurrence (HR 0.82, 95%CI: 0.30-2.28; p=0.71). Multivariable Cox regression analysis revealed high grade meningiomas (HR: 3.62, 95% CI: 1.60-8.22; p = 0.002), complete sinus invasion (HR: 3.00, 95% CI: 1.16-7.79; p = 0.024), and subtotal resection (HR: 3.10, 95% CI: 1.38-6.96; p = 0.006) portend increased risk of recurrence. CONCLUSIONS: This is the largest study to date that identifies predictors that confer increased risk of recurrence after resection of parasagittal and parafalcine meningiomas, which can be used to