Suppl 2 -S18 Purpose: The aim of this study was to identify predictive factors of biological behaviour and patient outcome after surgical resection of meningiomas. Methodology: We retrospectively reviewed 192 cases of meningiomas who had undergone surgical resection in the Department of Neurosurgery at Toronto Western Hospital the last 5 years. Our cohort consisted of 64 males and 128 females. Clinical, radiological, and pathological records were review for data regarding: patientssex, age,

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... r grade, tumor location, presence of peritumoral edema prior to surgical resection, and tumors largest diameter as a clinical measure of tumor size. All analyses were performed using IBM SPSS 20.0. Results: The incidence of peritumoral edema was significantly greater in males (45/64, 73%) than in females patients (64/128, 50.0%) (p=0.007). Meningioma location was significantly associated with presence of edema (p<0.001); olfactory meningiomas showed the greatest incidence of edema (71.4%) followed by convexity meningiomas (60.5%), abd sphenoid wing meningiomas (72.2%) (p<0.001). Tumors with larger extrameatal diameters (4.3cm vs. 3.5cm) were more likely to have peritumoral edema (p=0.001). The presence of residual tumor after surgical resection was more likely in meningiomas with higher grades p<0.001. Also, as expected, the grade of tumor was significantly correlated with the incidence of recurrence. Recurrence was also found to be more common in men (15.6%) than in women (4.7%) (p=0.01). Conclusion: The present study demonstrates that specific radiologic and histopathologic characteristics are significant predictors of tumor recurrence and patient outcome. CP13