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Single-Isocenter Frameless Volumetric Modulated Arc Radiosurgery for Multiple Intracranial Metastases
Steven K M Lau1, Kaveh Zakeri, Xiao Zhao
1Departments of ‡Radiation Medicine and Applied Sciences and §Surgery, Division of Neurosurgery, Moores University of California San Diego Cancer Center, La Jolla, California; ¶Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut.
Background:
Stereotactic radiosurgery (SRS) is a well-accepted treatment for patients with intracranial metastases, but outcomes with volumetric modulated arc radiosurgery (VMAR) are poorly described.
Objective:
To report our initial clinical experience applying a novel single-isocenter technique to frameless VMAR for simultaneous treatment of multiple intracranial metastases.
Methods:
We performed a retrospective analysis of 15 patients undergoing frameless VMAR for multiple intracranial metastases using a single, centrally located isocenter in the period 2009 and 2011. Of these, 3 patients were treated for progressive or recurrent intracranial disease. A total of 62 metastases (median, 3 per patient; range, 2-13) were treated to a median dose of 20 Gy (range, 15-30 Gy). Three patients were treated with fractionated SRS. Follow-up including clinical examination and magnetic resonance imaging (MRI) occurred every 3 months.
Results:
The median follow-up for all patients was 7.1 months (range, 1.1-24.3), with 11 patients (73.3%) followed until death. For the remaining 4 patients alive at the time of analysis, the median follow-up was 19.6 months (range, 9.2-24.3). Local control at 6 and 12 months was 91.7% (95% confidence interval [CI], 84.6%-100.0%) and 81.5% (95% CI, 67.9%-100.0%), respectively. Regional failure was observed in 9 patients (60.0%), and 7 patients (46.7%) received salvage therapy. Overall survival at 6 months was 60.0% (95% CI, 40.3%-88.2%). Grade 3 or higher treatment-related toxicity was not observed. The median total treatment time was 7.2 minutes (range, 2.8-13.2 minutes).
Conclusion:
Single-isocenter, frameless VMAR for multiple intracranial metastases is a promising technique that may provide similar clinical outcomes compared with conventional radiosurgery.
