Predicting Tumor Control After Resection Bed Radiosurgery of Brain Metastases
Neurosurgery - Current Issue
BACKGROUND:Stereotactic radiosurgery (SRS) to the resection bed of a brain metastasis is an important treatment option. OBJECTIVE:To 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. METHODS:We 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. RESULTS:Local 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 cm3, 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. CONCLUSION:Resection 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. ABBREVIATIONS:ARE, adverse radiation effectPTV, planned treatment volumeSRS, stereotactic radiosurgeryWBRT, whole-brain radiation therapyOriginal Article: http://journals.lww.com/neurosurgery/Fulltext/2013/12000/Predicting_Tumor_Control_After_Resection_Bed.19.aspx
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