The Outcome of Hypo-fractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas

• Published in: World neurosurgery 2016
• Main Authors: Teo, Mario, MD, Zhang, Michael, BA, Li, Amy, BA, Thompson, Patricia A., MSN, Tayag, Armine T., MSN, Wallach, Jonathan, MD, Gibbs, Iris C., MD, Soltys, Scott G., MD, Hancock, Steven L., MD, Chang, Steven D., MD
• Format: Article
• Language: English
• Subjects: Neurosurgery
• ISSN: 1878-8750
• DOI: 10.1016/j.wneu.2016.06.080

Abstract Objectives Stereotactic radiosurgery (SRS) for large vestibular schwannomas (VS) remains controversial. We studied the tumor local control and toxicity rates after hypo-fractionated SRS for VS > 3 cm. Methods 587 VS patients treated with SRS between 1998 and 2014 were retrospectively reviewed, identifying 30 Koos Grade IV VS. There were 6 patients with NF2, 8 with cystic tumors, 22 with solid tumors, 19 who underwent primary CyberKnife (CK), and 11 with > 3 cm after prior resection. Patients were treated by a median of 3 fractions at 18 Gy. Results After a median 97 months , the 3- and 10-year Kaplan-Meier estimates of local control were 85% and 80% respectively, with 20% requiring salvage treatment. For patients who had prior tumor resection rather than primary CK, there were 46% and 5%, respectively with progression, and 3-year control rates of 71% and 94% (p=0.008). Tumor control was also lower among NF2 vs non-NF2 patients (40% vs 95%, p=0.0014). Among patients with good clinical baselines prior to CK, 88% were functionally independent (mRS 0-2), 88% had good facial function (HB I-II), and 38% had serviceable hearing (GR I-II) at last follow-up. Hearing worsening was more likely among patient treated with primary CK (33% vs 90%, p = 0.04). Conclusions Overall, 80% of large VSs were adequately controlled by CK with 97 months of median follow-up. Patients with previous surgery and NF2 also appeared to have higher rates of tumor progression, and less favourable functional outcomes.