The Outcome of Hypofractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas

• Published in: World neurosurgery 2016-09, Vol.93, p.398-409
• Main Authors: Teo, Mario, Zhang, Michael, Li, Amy, Thompson, Patricia A., Tayag, Armine T., Wallach, Jonathan, Gibbs, Iris C., Soltys, Scott G., Hancock, Steven L., Chang, Steven D.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; California - epidemiology; Comorbidity; Cystic; Disease-Free Survival; Dose Hypofractionation; Facial nerve; Female; Follow-Up Studies; Hearing Loss - diagnosis; Hearing Loss - epidemiology; Hearing Loss - prevention & control; Hearing preservation; Humans; Hypo-fractionated stereotactic radiosurgery; Longitudinal Studies; Male; Middle Aged; Neoplasm Recurrence, Local - diagnosis; Neoplasm Recurrence, Local - epidemiology; Neoplasm Recurrence, Local - prevention & control; Neurofibromatosis; Neuroma, Acoustic - diagnosis; Neuroma, Acoustic - epidemiology; Neuroma, Acoustic - surgery; Prevalence; Primary treatment; Radiosurgery; Retrospective Studies; Risk Assessment; Treatment Outcome; Vestibular schwannoma; Young Adult
• ISSN: 1878-8750; 1878-8769
• DOI: 10.1016/j.wneu.2016.06.080

Stereotactic radiosurgery (SRS) for large vestibular schwannomas (VS) remains controversial. We studied the tumor local control and toxicity rates after hypofractionated SRS for VS > 3 cm. A total of 587 patients with VS treated with SRS between 1998 and 2014 were reviewed retrospectively, and 30 Koos grade IV VSs were identified. There were 6 patients with neurofibromatosis 2 (NF2), 8 with cystic tumors, 22 with solid tumors, 19 who underwent primary CyberKnife (CK), and 11 with >3 cm after previous resection. Patients were treated by a median of 3 fractions at 18 Gy. 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 previous tumor resection rather than primary CK, the estimates 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 versus non-NF2 patients (40% vs. 95%; P = 0.0014). Among patients with good clinical baselines before CK, 88% were functionally independent (modified Rankin Scale score, 0–2), 88% had good facial function (House-Brackmann grade I–II), and 38% had serviceable hearing (Gardner-Robertson grade I–II) at last follow-up. Hearing worsening was more likely among patients treated with primary CK (33% vs. 90%; P = 0.04). 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 favorable functional outcomes.