Long-Term Outcomes of Vestibular Schwannoma Treated with Stereotactic Radiosurgery: A Retrospective Study from a Single Institution

Thursday, March 20, 2025

1:25 PM – 1:33 PM MST

Location: Grand I/II

Presenter(s)

David J. Park, MD, PhD, FCNS (he/him/his)

Clinical Assistant Professor
Stanford University
Stanford, California, United States

Contact Author(s)

AK

Ahed H. Kattaa, MD

Visiting Instructor
Stanford University
San Jose, California, United States

Co-Author(s)

jJ

juan J. Cardona, MD

visiting instructor
Stanford University, United States
ES

Elaheh Shaghaghian, MD

Visiting Instructor
Stanford University, United States
Amirhossein Akhavan-Sigari, MD

Research Fellow
Stanford University
Palo Alto, CA, United States
SR

Shagun Ravi Nasta, MD

visiting instructor
Stanford University, United States
HV

Harini Voruganti, MS

Undergraduate Student
Berkeley University, United States
IL

Isabelle Lee, MS

visiting instructor
Stanford University, United States
YH

Yusuke S. Hori, MD

Clinical Fellow
Stanford University, United States
SE

Sara C. Emrich, NP

Nurse Practitioner
Stanford University, United States
LU

Louisa Ustrzynski, NP, MBA

Nurse Practitioner
Stanford University, United States
AT

Armine Tayag, NP

Nurse Practitioner
Stanford University, United States
JA

John R. Adler, MD

Professor of Neurosurgery
Stanford University, United States
SC

Steven D. Chang, MD, MBA

Professor
Stanford University, United States

Objectives: : Vestibular schwannoma (VS) is a benign tumor arising from cranial nerve VIII, commonly affecting the internal auditory canal and the cerebellopontine angle. This study evaluates the long-term efficacy and safety of stereotactic radiosurgery (SRS) using CyberKnife, a platform pioneered at Stanford, highlighting our institution’s extensive long-term experience and data.

Methods: : We retrospectively analyzed a total of 344 VS cases treated with CyberKnife SRS from 1998 to 2014. Data included patient demographics, clinicopathology, radiology, and treatment details. Statistical analyses included Chi-square tests, Mann-Whitney U tests, independent t-tests, and Kaplan-Meier analysis.

Results: : The median follow-up was 157 months, representing one of the longest follow-up periods reported. The mean age was 51.9 years, with 50.9% female patients. The median tumor size was 1.7 cm, with a median target volume of 0.94 cc. Median maximum and prescribed doses were 22.5 Gy and 18 Gy, respectively. NF2 patients received higher doses (P=0.016) and had longer follow-up (P=0.012). NF2-associated tumors more frequently presented with higher Koos grades and required additional interventions (P=0.025). CN V deficits correlated with CN VIII symptom resolution (P=0.002). Notably, smokers (P=0.001) and non-hypertensive patients (P=0.001) had higher symptom resolution rates. Local recurrence was higher in those with prior surgery (P=0.048). Remarkably, local control rates were 100% at 2 years, 98.8% at 5 years, 94.2% at 15 years, and 89.3% at 25 years. Overall survival was 100% at 10 years and remained at 97.1% at 25 years.

Conclusion(s):: Our extensive long-term data confirm that CyberKnife SRS provides sustained local control and safety for VS treatment over decades, reinforcing its role as a reliable and effective management strategy pioneered at Stanford.