• Neal Luther, Douglas Kondziolka, Hideyuki Kano, Seyed H Mousavi, Johnathan A Engh, Ajay Niranjan, John C Flickinger, and L Dade Lunsford.
• *Department of Neurological Surgery and §Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania ‡Department of Neurosurgery, New York University Langone Medical Center, New York, New York.
• Neurosurgery. 2013 Dec 1; 73 (6): 1001-6; discussion 1006.

BackgroundStereotactic radiosurgery (SRS) to the resection bed of a brain metastasis is an important treatment option.ObjectiveTo identify factors associated with tumor progression after SRS of the resection bed of a brain metastasis and to evaluate patterns of failure for patients who eventually had tumor progression.MethodsWe performed a retrospective analysis of 120 patients who underwent tumor bed radiosurgery after an initial gross total resection. The mean imaging follow-up time was 55 weeks. The median margin dose was 16 Gy. Forty-seven patients (39.2%) underwent whole-brain radiation therapy before or shortly after SRS.ResultsLocal tumor control was achieved in 103 patients (85.8%). Progression-free survival was 96% at 6 months, 87% at 12 months, and 74% at 24 months. Recurrence most commonly occurred deep in the cavity (65%) outside the planned treatment volume (PTV) margin (53%). PTV, cavity diameter, and a margin dose < 16 Gy significantly correlated with local failure. For patients with PTVs ≥ 8.0 cm, local progression-free survival declined to 93% at 6 months, 83% at 12 months, and 65% at 24 months. Development or progression of distant metastases occurred in 40% of patients. Whole-brain radiation therapy was not associated with improved local control.ConclusionResection bed SRS for brain metastases provided excellent local control. The cavity PTV is predictive of tumor control. Because failure usually occurs outside the PTV, inclusion of a judicious 2- to 3-mm margin beyond the area of postoperative enhancement may be prudent.

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