Introduction: The aim of this study is to investigate the factors related to necessity of retreatment and to find any possible surgical nuances surgeons can add with the aid of modern neurosurgical techniques for meningiomas treated by Simpson grade IV resection.
Methods: This retrospective analysis included patients with World Health Organization grade I meningiomas treated by Simpson grade IV resection as their initial therapy at the University of Tokyo Hospital between January 1995 and April 2010.
Results: A total of 38 patients were included in this study. Regrowth of residual tumor was observed in 22 patients in a mean follow-up period of 6.1 years. Retreatment including re-resection or stereotactic radiosurgery due to regrowth of residual mass was performed for 20 of 22 tumors with regrowth. Risk factors related to significantly shorter retreatment-free survival were age younger than 50 years (p = 0.006), post-resection tumor volume of 4 cm3 or more (p = 0.016), no dural detachment (p = 0.001), and skull base location (p = 0.016). Multivariate analysis revealed that no dural detachment (hazard ratio 6.42, 95% confidence interval 1.41-45.0, p = 0.02) and skull base location (hazard ratio 11.6, 95% confidence interval 2.18-218, p = 0.002) were independent risk factors for early necessity of retreatment while post-resection tumor volume of 4 cm3 or more was not a statistically significant risk factor.
Conclusions: Compared to Simpson grade I, II, III resections, Simpson grade IV resections comprise highly heterogeneous groups of tumor. Despite the difficulty to collectively analyze those diverse data, our results draw attention to a favorable effect of dural detachment, instead of maximizing the resection rate, on long-term tumor control. Surgical strategy with an emphasis on detaching the tumor from the affected dura might be another important option in resection of high-risk meningiomas not amenable for gross total resection.
Patient Care: We believe that our research will contribute to reconciliation of long-term tumor control and less-invasiveness in the treatment of meningioma that are not amenable for gross total resection.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Learn the importance of detaching the tumor off of the dura for better long-term tumor control.