Predictors of Recurrence After Sub-total or Near-total Resection of Vestibular Schwannoma: Importance of Tumor Volume and Ventral Extension

Abstract

Objective:To evaluate the predictors of remnant tumor regrowth and need for salvage therapy after less than gross total resection (GTR) of vestibular schwannoma (VS).Study Design:Retrospective chart review.Setting:Tertiary neurotologic referral center.Patients:Patients who underwent VS resection between 2008 and 2019 either with GTR, near total resection (NTR), and subtotal resection (STR).Interventions:Microsurgical resection, salvage radiosurgery.Main Outcome Measures:Regrowth free interval, salvage free interval, tumor doubling rate.Results:Three hundred eighty five cases (GTR = 236, NTR = 77, and STR = 71) from 2008 to 2019 were included. STR cohort had much larger and complex tumors with significant differences in tumor volume, ventral extension and brainstem compression (p < 0.001). On single predictor analysis, tumor volume, ventral extension, brainstem compression as well as STR strategy was associated with significant increased risk of regrowth and need for salvage therapy. Multivariate analysis revealed STR strategy as significant predictor of regrowth (hazard ratio 3.79, p < 0.0005). Absolute remnant volume and extent of resection (EOR) did not predict regrowth. A small proportion of cases (NTR = 4%, STR = 15%) eventually needed salvage radiosurgery with excellent ultimate local tumor control with no known recurrence to date.Conclusions:Conservative surgical strategy employing NTR or STR can be employed safely in large and complex VS. While there is increased risk of regrowth in the STR cohort, excellent local control can be achieved with appropriate use of salvage radiosurgery. No disceret radiologic or operative predictors of regrowth were identified.

Outcomes of Extended Middle Fossa Approach for Petroclival Tumors in the Elderly

“…Unfortunately, there is a lack of standardization even when reporting NTR or STR, when it comes to the Toronto criteria versus the San Francisco criteria. 24 Moreover, the consistency of reporting the residual disease, at what interval and what volume and when to radiate are even more variable. 24,25 While the decision of when to radiate a salvage case is beyond the scope of this study, it is important to note that even among the literature, there is no consistency on timing.…”

“…24 Moreover, the consistency of reporting the residual disease, at what interval and what volume and when to radiate are even more variable. 24,25 While the decision of when to radiate a salvage case is beyond the scope of this study, it is important to note that even among the literature, there is no consistency on timing. Early versus late can be less than 6 months or greater than 6 months after the initial intervention, and what the regimen of the radiation should be is also keenly debated.…”