Background:Recently the relevance of Simpsons resection grade as a prognostic factor for recurrence of WHO grade I meningiomas was challenged, contradicting many previous scientific reports and traditional neurosurgical teaching.
Objective:To study whether the predictive value of Simpson resection grade with respect to meningioma recurrence and overall survival is outdated or still valid.
Material & Methods:All patients ≥16 years who underwent primary craniotomies for convexity meningiomas at the Oslo University affiliated hospitals (Rikshospitalet and Ullevål University Hospital) in the period 01.01.1990 – 27.01.2011 were included. Overall survival (OS) and retreatment-free survival (RFS) rates were related to patient- and surgery-specific factors.
Results:Included in the study were 391 consecutive patients. Median age was 60.1 years (range 19 - 92). Female-to-male ratio was 2.1:1. WHO grade was grade I in 352 (90.3%), grade II in 22 (5.6%) and grade III in 16 (4.1%). Follow-up was 100%. Median follow-up time was 7.1 years (range 0.0 – 20.9 years) and total observation time was 3147 patient-years. The 1-, 5- and 10-year OS were 96%, 89% and 78%, respectively. Age, gender, WHO-grade and Simpson grade were significantly associated with OS. The 1-, 5- and 10-year RFS were 99%%, 94% and 90%, respectively. Simpson resection grade and WHO grade were significantly associated with RFS. Odds ratio for recurrence after Simpson resection grade 2/3 and 4/5 were 5.2 and 26.1 times higher than after Simpson grade 1 resection, respectively.
Conclusions: Simpson grade 1 resection should still be the goal for convexity meningiomas.