Simpson grade: an opportunity to reassess the need for complete resection of meningiomas.

BACKGROUND: The relevance of the Simpson grading system as a predictor of meningioma progression or recurrence in modern neurosurgical practice has recently been called into question. The aim of our study was to compare the risk of progression/recurrence of tumours that had been treated with different Simpson grade resections in a contemporary population of benign (WHO grade I) meningioma patients.

METHOD: One hundred eighty-three patients with histologically confirmed WHO grade I meningioma were retrospectively analysed. All patients underwent first-time craniotomy as their initial therapy between 2004 and 2012. Univariate analysis was performed using log-rank testing and Kaplan-Meier analysis for progression/recurrence-free survival. Multivariate analysis was performed using Cox proportional hazards regression modelling.

RESULTS: The three-year progression/recurrence-free survival rates for patients receiving Simpson grade 1, 2 or 4 resections were 95 %, 87 % and 67 %, respectively. Simpson grade 4 resections progressed/recurred at a significantly greater rate than Simpson grade 1 resections (hazard ratio [HR] = 3.26, P = 0.04), whereas Simpson grade 2 resections did not progress/recur at a significantly greater rate than Simpson grade 1 resections (HR = 1.78, P = 0.29). Subtotal resections progressed/recurred at a significantly greater rate than gross-total resections (HR = 2.47, P = 0.03).

CONCLUSIONS: Tumours that undergo subtotal resection are at a significantly greater risk of progression/recurrence than tumours that undergo gross-total resection. Gross-total resection should therefore be the aim of surgery. However, given modern access to follow-up imaging and stereotactic radiosurgery, these results should not be used to justify overly 'heroic' tumour resection.