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The Volumetric Response of Brain Metastases After Stereotactic Radiosurgery and Its Post-treatment Implications

Sharpton, Suzanne R. MD*; Oermann, Eric K. BS; Moore, Dominic T. PhD§; Schreiber, Eric PhD; Hoffman, Riane BA; Morris, David E. MD; Ewend, Matthew G. MD

doi: 10.1227/NEU.0000000000000190
Research-Human-Clinical Studies

BACKGROUND: Changes in tumor volume are seen on magnetic resonance imaging within weeks after stereotactic radiosurgery (SRS), but it remains unclear what clinical outcomes early radiological changes portend.

OBJECTIVE: We hypothesized that rapid, early reduction in tumor volume post-SRS is associated with prolonged local control and favorable clinical outcome.

METHODS: A retrospective review of patients treated with CyberKnife SRS for brain metastases at the University of North Carolina from 2007 to 2009 was performed. Patients with at least 1 radiological follow-up, minimal initial tumor volume of 0.1 cm3, no previous focal radiation, and no recent whole-brain radiation therapy were eligible for inclusion.

RESULTS: Fifty-two patients with 100 metastatic brain lesions were analyzed and had a median follow-up of 15.6 months (range, 2-33 months) and a median of 2 (range, 1-8) metastatic lesions. In treated metastases in which there was a significant tumor volume reduction by 6 or 12 weeks post-SRS, there was no local progression for the duration of the study. Furthermore, patients with metastases that did not reduce in volume by 6 or 12 weeks post-SRS were more likely to require corticosteroids (P = .01) and to experience progression of neurological symptoms (P = .003).

CONCLUSION: Significant volume reductions of brain metastases measured at either 6 or 12 weeks post-SRS were strongly associated with prolonged local control. Furthermore, early volume reduction was associated with less corticosteroid use and stable neurological symptoms.

ABBREVIATIONS: CI, confidence interval

OS, overall survival

RCC, renal cell carcinoma

SBS, Schwarz bayesian criterion

SRS, stereotactic radiosurgery

WBRT, whole-brain radiotherapy

*Department of Internal Medicine, University of California San Francisco, San Francisco, California;

Department of Neurological Surgery, University of North Carolina School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North California;

§Department of Biostatistics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North California;

Radiation Oncology, University of North Carolina School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North California

Correspondence: Matthew G. Ewend, MD, Department of Neurosurgery, University of North Carolina at Chapel Hill, CB #7060, Chapel Hill, NC 27599. E-mail: ewend@med.unc.edu

Received August 28, 2012

Accepted September 19, 2013

Copyright © by the Congress of Neurological Surgeons