Time after vestibular schwannoma treatment: Annual risk of tumor recurrence after radiosurgery or microsurgery
Sophie Wang (Tübingen), Gerhard Horstmann (Krefeld), Albertus van Eck (Krefeld), Marcos Tatagiba (Tübingen), Georgios Naros (Tübingen)
Although vestibular schwannoma (VS) are a benign tumor entity (CNS Grade I), both available treatments radiosurgery (SRS), and microsurgery (SURGERY) necessitate long-term follow-up for potential tumor recurrence/progression. However, the actual long-term risk for tumor recurrence/progression remains uncertain. We aimed to obtain estimates of annual risk of tumor recurrence during post-interventional follow-up in VS.
This is a retrospective dual-center cohort study enrolling consecutive patients with sporadic VS between 2005 and 2012. Recurrence-free-survival was assessed radiographically by contrast-enhanced MR imaging. Extent of resection was classified in the 3 months postoperative MR imaging according to residual tumor (STR) or gross-total-resection (GTR).
N=1'230 patients were included in this study. 66% were treated with SRS and 34% with SURGERY. The overall incidence of tumor progression in SRS-treated VS was 11%. In SURGERY, the incidence of tumor recurrence was significantly lower at 5%. The risk for VS recurrence was 1.7% per year in SRS-treated VS compared to 1.3% per year in SURGERY. After SURGERY, the risk for recurrence was significantly lower in GTR was achieved (1.0% per year) compared to STR (6.3% per year). In SRS-treated VS, the yearly-risk was increased with tumor size yielding in an annual risk of 0.4% in Koos I, 1.9% per year in Koos II, 2.0% per year in Koos III, and 1.6% per year in Koos IV.
The overall annual risk for tumor progression was lower in SURGERY compared to SRS, especially in GTR. STR dramatically increases the recurrence risk. The risk for tumor progression in SRS-treated VS depends on tumor size.