J Neurol Surg B
DOI: 10.1055/s-0039-1692642
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Longitudinal Radiographic Outcomes of Vestibular Schwannoma in Single and Fractionated Stereotactic Radiosurgery: A Retrospective Cohort Study

Mohamed H. Khattab
1  Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Neil B. Newman
1  Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
David M. Wharton
2  Vanderbilt University School of Medicine, Nashville, Tennessee, United States
,
2  Vanderbilt University School of Medicine, Nashville, Tennessee, United States
,
Guozhen Luo
1  Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Nauman F. Manzoor
3  Department of Otolaryngology - Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Alejandro Rivas
3  Department of Otolaryngology - Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
L. Taylor Davis
4  Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Lola B. Chambless
5  Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Albert Attia
1  Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
,
Anthony J. Cmelak
1  Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
› Author Affiliations
Further Information

Publication History

14 January 2019

20 March 2019

Publication Date:
12 June 2019 (online)

Abstract

Management of vestibular schwannoma (VS) includes stereotactic radiosurgery (SRS) in single or fractionated treatments. There is a paucity of literature on the three-dimensional (3D) volumetric kinetics and radiological changes following SRS and no consensus on appropriate post-SRS surveillance imaging timeline. This is a retrospective cohort study with institutional review board approval. A total of 55 patients met study criteria. We collected volumetric kinetic data in VS treated with SRS over time using a target volume contouring software. We also tracked radiographic phenomena such as pseudoprogression and necrosis. A secondary objective was to describe our overall treatment success rate and any failures. For all treatments groups, pseudoprogression most typically occurred within 12 months post-SRS, after which tumor volumes on average normalized and then decreased from pretreatment size at the last follow-up. Only two patients required salvage therapy post-SRS and were considered SRS treatment failures. Both patients were in the five-fraction cohort but with a lower biologically equivalent dose. Our study is first to collect 3D volumetric kinetics of VS following single and fractionated SRS in contrast to extrapolations from single and two-dimensional measurements. Our longitudinal data also show initial increases in volume in the first 12 months post-SRS followed by later declines, setting up interesting questions regarding the utility of early posttreatment surveillance imaging in the asymptomatic patient. Finally, we show low rates of treatment failure (3.6%) and show in our cohort that SRS dose de-escalation posed a risk of treatment failure.